She is only the second first lady in American history born outside of the United States, in Slovenia. The only other foreign-born first lady was Louisa Catherine Johnson, the wife of John Quincy Adams, who was born in England.
Trump is also the only FLOTUS who grew up in a Communist country, back when Slovenia was part of Yugoslavia. Though money was tight for many people in the small town of Sevnica, people who knew Melanija Knavs back then said she was "always very fancy" and "never wore anything from the store."
Trump is the only first lady to be her husband's third spouse. Donald Trump was previously married to Marla Maples until 1999, and before that, Ivana Trump until 1992.
She's also the only first lady whose first language wasn't English.
Trump is a noted polyglot. She can speak more languages than any first lady before her: English, French, German, Italian, and Serbian, in addition to her native Slovenian.
Trump was a successful model, known for her appearances in Sports Illustrated, Vanity Fair, Vogue, Harper's Bazaar, and GQ. She's also the only first lady to have posed nude for magazines, including a British GQ photo spread in 2000.
You might also recognize Trump from her appearance alongside the Aflac duck in a 2005 mad-scientist-themed insurance commercial.
While she towers over many people she meets, Trump is actually tied for tallest first lady with Michelle Obama and Eleanor Roosevelt, who were also 5-foot-11.
In addition to her modeling career, Trump was also a successful businesswoman, who launched her own jewelry and caviar-based skincare lines in 2010 and 2013, respectively.
Trump is only the second first lady who is a practicing Catholic — the first was Jaqueline Kennedy. That fact made Trump's visit to the Vatican last May particularly meaningful; when she met Pope Francis she held out rosary beads for him to bless.
Unlike other first ladies, Trump also delayed her move into the White House until five months into her husband's presidency.
Though some critics speculated that Trump was trying to shun her role as first lady, the Trumps have said the delay was because they wanted their son, Barron Trump, to finish out his 5th-grade school year in New York City.
But when she did finally move to Washington, the members of the permanent White House staff instantly adored her. It was her thoughtful, everyday interactions with the staff members that made Trump stand out among other first families, former staffers have said.
The Trumps reportedly "spend very little to no time together," sleep in different bedrooms, and operate on completely separate schedules, according to some White House aides and friends.
There's even a conspiracy theory going around Washington that Trump doesn't live in the White House at all, and instead lives in a house with her parents near her son's school.
But according to the first lady's spokeswoman, the rumor is "1,000% false. We laugh at it all the time."
Despite the White House's best efforts, the Trumps' marriage remains one of the greatest curiosities among the press and public — especially as controversy continues to grow around the president's alleged affair with porn star Stormy Daniels and his lawyer's $130,000 hush-money payment.
Melania Trump hasn't yet spoken out about it. Some speculate that refusing to hold his hand, or taking separate routes to events, are telltale signs of conflict. But for the foreseeable future, it looks like their unique marriage will stay private.
Trump stands out from her predecessors with her quiet manner and reserved personality. Her friends have described her as a homebody who often retires from events early and avoids being the center of attention.
But it's tough to stay private when you're one of the most recognizable women in the world.