Titles: Singer (Beyoncé), rapper and entrepreneur (Jay Z) Country: US Age: 34 (Beyoncé), 45 (Jay Z) Music's biggest power couple, Beyoncé and Jay Z turn nearly everything they touch into gold, which has helped them mint a combined fortune of $950 million. Beyoncé shocked the music industry in 2013 when she released an album on iTunes without promotion — it went on to sell over 5 million copies thanks to hits like Drunk in Love and Partition. Jay Z is consistently one of the highest earners in music, reportedly raking in $56 million last year through his many ventures, including his Roc Nation music label and its sports division. Though his streaming service, Tidal, encountered some turbulence — the hip-hop mogul himself forgot he owned it — Jay Z is still just about everywhere in the entertainment industry.Title: Chairman, CEO of Las Vegas Sands Country: US Age: 82 The King of Las Vegas is expected to dole out millions by this time next year, taking a gamble on one of his favorite things: politics. The casino magnate, who owns 13 private jets, is a staunch supporter of the Republican party, famously donating tens of millions from his $25 billion fortune to past candidates such as Newt Gingrich. For his day job, he runs Las Vegas Sands — parent of the Venetian Resort and Casino and Sands China, a subsidiary that's planning to open its fifth casino in Macau next year. And while Adelson’s vision to make China the gambling capital of the world isn't outlandish considering his industry dominance, it may not pan out under political restrictions and President Xi Jinping's push to make Macau a family-friendly destination. Amid the flux, Sheldon’s fortune has reportedly lost several billions in the past year after a 25% decline in the price of Las Vegas Sands stock.Title: Chairman, CEO of IBM Country: US Age: 58 Last year, IBM CEO Ginni Rometty had to break some tough news: The tech company would be abandoning its years-long promise to hit $20 earnings per share by 2015. But the company's top leader has hatched a new plan: IBM will invest $4 billion to grow $40 billion in revenue in areas such as cloud computing, mobile, and big data by 2018. The plan would nearly double what IBM is making in these markets now, though it also means straying from the hardware focus that's defined IBM for decades. Rometty's mandate is to keep one of tech's most iconic companies — which employs 380,000 people, on par in size with the population of New Orleans — relevant and profitable for the long haul, even if it means changing some of the most fundamental things about the company. The IBM lifer isn't apologizing for adapting. Reinvention is not about protecting your past, she said at the Fortune Global Forum earlier this year.Title: Founder, CEO of Blackstone Group Country: US Age: 68 Steve Schwarzman is the unparalleled king of private equity, with a fortune of $11 billion that includes splashy homes in Manhattan, the Hamptons, Jamaica, and Saint-Tropez. His vaunted buyout firm Blackstone Group is the largest on earth, with $334 billion in assets under management, and it has completed some of the most high-profile acquisitions in the industry. The company’s $26 billion leveraged buyout of the Hilton hotel chain in 2007 is considered by some the most profitable of all time. Schwarzman had a short but prosperous career with investment bank Lehman Brothers before leaving in 1985 to start Blackstone with ousted Lehman CEO Peter Peterson. They opened shop with $400,000, but Schwarzman gained a reputation as savvy and lucrative dealmaker, and Blackstone grew into a juggernaut. In 2014 it generated a record $7.5 billion in revenue. Never satisfied, Schwarzman wants Blackstone to double in size in the next eight years. Schwarzman donated $150 million in May to build a student commons at Yale.Title: CEO, Microsoft Country: US Age: 48 Since becoming Microsoft's third CEO last year, Satya Nadella has been busy helping the technology company become relevant again. While Microsoft is still a software giant — it pulls in $95 billion in sales — it's far from its former glory as tech's innovative, undisputed leader. But Nadella, a Microsoft veteran of 23 years, has made significant progress in rejuvenating the company: He successfully released Windows 10, a huge hit that attracted over 110 million users in three months; he converted Microsoft rivals like Salesforce and Oracle into partners; he launched Microsoft into the growing Internet of Things market with a new database, cloud service, and big-data analysis service; and he oversaw Microsoft's biggest layoff round ever while still maintaining his likability among employees.Title: CEO, Tesla and SpaceX Country: US Age: 44 The man who believes there's no such thing as business, only the pursuit of a goal has invested in, founded, or run 18 companies to date, including two of the most innovative technology firms in America: Tesla Motors and SpaceX. It was a big year for both companies, with retail deliveries of the Tesla Model X crossover vehicle starting in September and the launch (and failure) of a SpaceX rocket bound for the International Space Station in June. Anticipation is already high for the mass-market Model 3 sedan, which Tesla plans to unveil next March, and another SpaceX supply launch set for December. Musk, who first hit it big cofounding PayPal in the late 1990s, has a growing fortune of more than $11 billion that enables him to experiment with technology of the future. In January, he announced via Twitter that he would build a five-mile Hyperloop test track to invite students and companies to test out their ideas for the high-speed transportation system. He also donated $10 million to the Future of Life Institution this year to keep artificial intelligence safe and beneficial to humans. Title: Founder, executive chairman of Oracle Country: US Age: 71 Oracle's billionaire cofounder Larry Ellison stepped down as the company's CEO last year but hasn't pumped the brakes: He still serves as chairman and CTO of the $38 billion (sales) database and software titan. Ellison announced plans this year for Oracle to take over as the primary provider of cloud-computing products and services, revealing at the company's tech conference in October that 20% of its customers — and counting — bought tech via the cloud rather than traditionally. Ellison, who routinely ranks as one of the 10 richest people in the world, holds a fortune of nearly $50 billion and a growing real-estate portfolio that spans the globe. His latest side project? Reviving the sport of tennis through investments at the fifth grand slam site in Indian Wells, California, and as lead sponsor for the Intercollegiate Tennis Association. Ellison is determined to restore tennis to prominence in the US and make the game more profitable globally — something he also recently accomplished with sailing.Title: CEO, OWN Country: US Age: 61 Worth nearly $3 billion, Oprah Winfrey is the only black female billionaire in the US. Despite a traumatic upbringing of living in poverty and enduring years of physical and sexual abuse, Winfrey became one of the most successful and beloved media personalities of the 21st century. Winfrey is the founder of the award-winning production studio Harpo Productions — responsible for the 2014 critical darling Selma — and the Oprah Winfrey Network. She also owns the The Oprah Winfrey Show, which brought in $300 million a year at its peak. She's a top cultural influencer, particularly among women, with a book club that is followed with cult-like dedication and an annual favorite things gift guide. Recently, she also extended the Oprah effect to the weight-loss industry when she bought a 10% stake in Weight Watchers in October and caused the stock to jump 105% as a result. Title: CEO of Exxon Mobil Country: US Age: 63 Rex Tillerson runs the world's largest publicly traded oil company, commanding about 75,000 employees and generating nearly $400 billion in annual sales. But the oil industry can be a beast of its own, regardless of a company's size. After a joint venture in the Arctic Sea between Exxon Mobil and the Russian firm Rosneft went up in smoke because of sanctions against Russia, Tillerson said in March that Exxon had been compensating by cutting costs and ramping up production in US shale fields. The company also came under investigation in November after reports suggested the company had for decades lied to the public about climate-change data. The lifelong Texan and Exxon employee will reach the company's mandatory retirement age of 65 in 2017, but until he steps down, Tillerson retains control over one of the wealthiest and most influential companies on the planet. Title: CEO of Bloomberg LP Country: US Age: 73 Michael Bloomberg is back — and he’s making sure his presence is known. After leaving Bloomberg LP, the financial data and media giant that he founded in 1981, and spending 12 years as mayor of New York City, Bloomberg was expected to devote his time to giving away his immense fortune, which stands at $42 billion. Instead, Bloomberg made waves by returning to the helm of his company in 2014, effectively ousting CEO Dan Doctoroff. Bloomberg didn't return as a figurehead — he immediately began shaking up the company. The newsroom saw layoffs, a management overhaul, and a website relaunch — as well as the exits of news head Matthew Winkler and top digital editor Joshua Topolsky — as Bloomberg flexed his authority over the company. The former mayor has had less luck asserting his vision over public policy. Though he effectively instituted a smoking ban in New York City, his efforts to eradicate big sodas fizzled out in the courts last year. He has pledged $50 million to combat the NRA, though little progress has been made on gun control thus far. Title: CEO of Apple Country: US Age: 54 Tim Cook runs the most valuable company on the planet in Apple, which is worth $645 billion. Under Cook's continued direction as CEO, 2015 has been one of the company's best years yet. Chief among Cook's 2015 successes has been the launch of Apple Music, the company's music-streaming service. The service went live in June and as of October counted 6.5 million paid subscribers and another 8.5 million people using the free trial service. And the iPhone is more popular than ever. At the company's annual fall event, Cook unveiled the iPhone 6s and iPhone 6S Plus, which sold 13 million in the first weekend, shattering previous records. Lately, Cook has been alluding to a forthcoming massive change in the auto industry, sparking rumors that an Apple Car is on the horizon. Cook was presented with the Human Rights Campaign Visibility Award this year where he spoke about his deeply personal decision to come out as gay: I wanted to lend my voice to people who might not be ready to exercise theirs, he said.Titles: Board members and controlling shareholders of Walmart Country: US Ages: 71 (Rob) and 67 (Jim) Rob and Jim Walton control perhaps the most powerful company on earth in the mega-retailer Walmart, which employs 2.2 million people in 28 countries and generates annual revenues of $486 billion. Combined, the Walton brothers' fortunes are worth more than $60 billion. Their father, founder Sam Walton, warned his children not to sell their stakes and to keep the company under family control, writing in his book, If you start any of that foolishness, I'll come back and haunt you. Sam and Rob have heeded his wishes. While neither manages day-to-day operations, both sit on the board, and the company remains majority-owned by the Walton family. Rob stepped down as chairman of the company in June 2015 after 23 years on the job, and his son-in-law Gregory Penner succeeded him. The company, long maligned for its low pay, announced in February 2015 it would increase wages for 500,000 US employees.Title: Cofounder, president of Alphabet Country: US Age: 42 Along with fellow cofounder Larry Page, Sergey Brin helped orchestrate Google’s massive restructuring, announced in August. The move made Google a subsidiary of a new holding company called Alphabet, run by Brin as president and Page as CEO. All of Google’s other ventures, such as Nest and Google X, are now separate companies under the Alphabet umbrella as well. The tech conglomerate generated $66 billion in sales in 2014. The restructuring frees the founding duo from the nitty-gritty details of running the massive company, instead allowing them to focus on exploring inventive new moon shot projects and ideas. With top talent and an abundance of resources at their disposal, the company has already made automated homes and self-driving cars a reality. Brin, who emigrated from Moscow to the US as a child, connected with Page in 1995 at Stanford, where they were each pursuing a Ph.D. They founded Google three years later, and today Brin and Page have personal fortunes of $38 billion and $42 billion today, respectively. Title: Chairman, CEO of JPMorgan Chase Country: US Age: 59 For a decade now Dimon has helmed JPMorgan Chase, the largest commercial bank in the US with $2.6 trillion in assets, and during his tenure he’s become one of the most respected voices in finance. His performance has also made him one of the few bank CEOs to become a billionaire. Dimon attained Wall Street rock-star status after the financial crisis. No major bank weathered the collapse as well as JPMorgan did under Dimon's guidance, earning him praise for the company’s “fortress balance sheet” and ability to make a profit amid the downturn. But his reputation took a hit in 2012 with the more than $6 billion loss incurred by the London Whale trading scandal, which resulted in stiff fines and a slew of lawsuits, some still ongoing. JPMorgan remains exceptionally profitable though, reporting record earnings of $21.8 billion in 2014. He has recovered from a recent bout with throat cancer, and he said in September he’s not planning on retiring anytime soon. Title: Founder, CEO of BlackRock Country: US Age: 63 Few have more responsibility for the US's economic well-being than Fink — CEO of BlackRock — the world’s largest asset-management firm. After rising to prominence and then flaming out on Wall Street — he was forced out at investment bank First Boston after losing $100 million on a poor interest-rate bet — he started BlackRock in 1988. It quickly grew into one of the largest money managers in the country. Fink is well regarded as a master of risk analysis and one of the savviest leaders in finance. His prowess and the company’s state-of-the-art risk-management system (dubbed “Aladdin”) made BlackRock a go-to adviser for sorting out toxic assets during the financial crisis, both to top banks and the US government. Today he’s trusted with overseeing $4.5 trillion in assets, a large chunk of it comprised of the hard-earned dollars from the average US citizen’s pension or retirement account. Fink is a popular and often speculated potential candidate for US Treasury secretary. Title: Founder and CEO of Facebook Country: US Age: 31 The leader of the world’s largest social network had a prosperous year. In May, Facebook-owned virtual-reality company Oculus VR made a buzzworthy announcement: It will finally sell its first consumer headset, Oculus Rift, starting early next year. A few months later, Facebook announced for the first time that its site had a billion users in a single day and 8 billion daily video views, double the number it reported in April. The company's stock is up about 40% through November 2015, and as a result Mark Zuckerberg’s net worth has soared to $47.6 billion. The Facebook founder also continues to invest hundreds of millions of his personal wealth in education, mainly through Startup:Education, a nonprofit he and his wife, Priscilla, founded in 2010 to improve schools in the Bay Area, and AltSchool, a company that promotes personalized education. He also gave $100 million to Newark, New Jersey's public schools, with disappointing results. After revealing in a July Facebook post that the couple is expecting their first child, they’ve announced plans to open a K-12 school in Palo Alto by next year that provides both education and health care to low-income families. Title: Cofounder, CEO of Alphabet Country: US Age: 42 Larry Page made some major moves this year, starting with a massive overhaul of Google’s business structure in August. He announced via press release that Google would become a subsidiary of new holding company Alphabet, which would oversee all of Google’s ventures, such as Nest, Calico, and Google X, as standalone entities. Previously the chief executive of Google, Page moved up to helm Alphabet as CEO, leaving company veteran Sundar Pichai in his spot. The change became official in October, and Page even dropped Google’s famous “don’t be evil” slogan from the new company. Page cofounded Google with Sergey Brin, who will help run Alphabet as president, in 1998, and they've earned fortunes of $42 billion and $38 billion today, respectively. The pair grew the company from a Ph.D project at Stanford into one of the biggest and farthest-reaching tech companies in the world. In addition to its ubiquitous search engine, the company has its hands in everything from home automation and self-driving cars to prolonging human life.Title: CEO, Amazon.com Country: US Age: 51 Amazon.com is an undeniable superpower in e-commerce. The company, which generates $89 billion in sales but has often failed to turn a net profit, surprised investors in July by reporting quarterly earnings of $92 million, handily beating analyst expectations. Amazon stock shot up, making founder and CEO Jeff Bezos worth an estimated $55 billion. Despite negative media reports in August claiming Amazon’s warehouses are high-pressure, toxic work environments — claims Bezos disputed — the company has continued to thrive. This year, Bezos led the growth of Amazon Web Services, the company’s cloud-computing branch, announced a plan for high-speed package delivery via drones, and opened Amazon’s first brick-and-mortar bookstore in Seattle. Bezos' privately owned space company Blue Origin successfully launched its first spacecraft this year and has plans to test rocket engines and launch manned rockets within the next decade.Title: CEO of Fidelity Country: US Age: 53 In late 2014, Abigail Johnson succeeded her father Edward as CEO of Fidelity, the second-largest mutual fund company in the US, which manages more than $2 trillion in assets. Johnson keeps a low profile, but it’s no secret she was groomed to take over the company from an early age. She started working at the firm in high school, and officially joined Fidelity as an analyst in 1988. Since 2012, Johnson had served as president. Johnson wasn't slow to wield her power and effect change after assuming the top role last year, quickly moving to cut costs and fire ineffective managers. She's no stranger to power plays, reportedly maneuvering to oust her father in 2004 over a disagreement in vision (the effort failed, and Edward remains the chairman of the company). Not only is the new Fidelity CEO responsible for millions of Americans' retirement accounts, but through her roughly 24% stake in the company, Johnson holds a personal fortune of $18.5 billion, making her one of the wealthiest women in the world.Title: Cochair, trustee of the Bill and Melinda Gates Foundation Country: US Age: 60 Gates cofounded Microsoft in 1975 with childhood friend Paul Allen, building an iconic software company and becoming the richest man on earth in the process, with a net worth of $87.3 billion. Though he still sits on the company’s board, he’s no longer actively involved in Microsoft. Instead, Gates is fixated on giving away his wealth and running one of the most powerful charities in the world with his wife, Melinda. They founded the Bill and Melinda Gates Foundation in 2000 after reading an article about curable diseases causing millions of child deaths in developing countries. Since then, the organization has given away $34.5 billion to an array of causes, including efforts to eliminate HIV, malaria and many other infectious diseases. They also support agricultural development, emergency relief, global libraries, urban poverty, and education. Gates and good friend Warren Buffett started the Giving Pledge to encourage billionaires to follow their lead and give away half or more of their wealth — 135 have signed up.Titles: CEO (Charles), executive VP (David) of Koch Industries Country: US Ages: 80 (Charles), 75 (David) Billionaire brothers Charles and David Koch run multifaceted conglomerate Koch Industries, the second-largest private company in America. Outspoken in the world of conservative politics, the Koch brothers, who have a combined net worth of $87 billion, wield a heavy influence over the upcoming 2016 presidential race. The two have publicly announced they're considering backing Republican candidate and former HP CEO Carly Fiorina for president. But they, along with their vast donor network, plan on pitching in a total of $889 million during the 2016 election cycle. Though politically divisive, the brothers' business success is undeniable. The company employs 100,000 people and generates $115 billion in sales from its diverse company, which makes everything from petrochemicals and Dixie Cups to raw clothing materials.Title: Chair of the Board of Governors of the Federal Reserve Country: US Age: 69 As the head of the Federal Reserve — the first woman to hold the job — Janet Yellen is the guardian of the US economy. The results have been good so far: The US is closing out the year with a period of growth, adding 271,000 jobs in October and lowering unemployment to 5%, according to the latest jobs report. The strong economic performance has many speculating that an interest rate hike from the Fed is imminent. It would be the first in almost a decade. It's a hefty decision with profound economic implications, and investors and company executives worldwide parse Yellen's every word for hints to her plans. A small rate hike would indicate the economy is thriving and strong, but some worry that lifting rates too early will damage individuals' spending ability and hamper growth. But too much growth and improvement in the labor market without a rate hike could lead to inflation. Either way, Yellen holds a position of immense power, and her decision will affect the entire country.Title: CEO, Berkshire Hathaway Country: US Age: 85 Berkshire Hathaway CEO Warren Buffett bought his first stock at age 11 and never looked back. Since then, Buffett has continued to amass a fortune of $65 billion through a near-clairvoyant knack for making smart, long-term bets on companies like Coca-Cola and American Express. His shareholder letters are a must-read for investors looking to glean his wisdom. His company has grown exponentially since he took over in 1964: $1,000 invested in Berkshire Hathaway stock then would be worth more than $10 million today. It remains one of the titans of the business world, announcing its largest acquisition ever in August with the $37.2 billion buyout of nuts and bolts maker Precision Castparts. Buffett is a friend of Microsoft cofounder Bill Gates, whom he collaborated with on the Giving Pledge, a promise for billionaires to give away at least 50% of their wealth to charity. Buffett has given away nearly $3 billion in each of the past two years, and $21.5 billion in his lifetime.Title: US president Country: US Age: 54 President Barack Obama presides over the world's most influential country, giving him unparalleled responsibility and power. He's caretaker of the largest economy, and he's helped nurse it back to health since the financial crisis. Since taking office in early 2009 — amid a full-blown recession — the US has grown its GDP by $3 trillion, to $17.4 trillion, and in October unemployment hit 5%, the lowest mark since 2008. His legacy-making overhaul of the health-care system has helped trim the uninsured rate by a third, and it has now survived multiple Supreme Court challenges. Obama's international track record is mixed. As commander-in-chief of the world's largest military — more than 2 million active and reserve forces and a defense budget of $560 billion — he's taken heat for failing to deal adequately with the growing turbulence in the Middle East, highlighted by the bloody Syrian civil war, the rise of ISIS, and the Taliban's growing strength in Afghanistan. Relations with longtime ally Israel have grown icy. Yet his sway in foreign affairs is still strong, as evidenced by his historic move to warm ties with Cuba and the momentous nuclear deal he brokered with Iran. He may have just a year left in office, but Obama isn't sitting idle: In November he flexed his power again, killing off the controversial Keystone XL pipeline proposal once and for all, arguing it would have harmed the environment without improving US energy security.