Amazon has a big leadership hole to fill with the departure of advertising exec Seth Dallaire. Here are five insiders that ad execs say are his likely successor.

• Seth Dallaire recently left his role as VP of global advertising sales and marketing at Amazon Advertising to be CRO at Instacart, creating a gap in Amazon's leadership.
• Dallaire was the face of Amazon's burgeoning advertising business and was the rare public figure who attended industry conferences and events to mingle with advertisers.
• Business Insider asked five agencies close to Amazon who they thought would replace Dallaire, and based on their knowledge of the company, they named five people they believed were being considered.
• The people they listed are internal executives with varying seniority and roles.
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When advertising exec Seth Dallaire recently left Amazon to be CRO of Instacart, Amazon lost a big name behind its growing but still nascent advertising business.

Amazon has increasingly emerged as a competitor to Facebook and Google, but the e-commerce giant keeps a low profile at industry events or conferences. Dallaire was the face of Amazon's advertising business and a rare exception to its notoriously closely guarded strategy. He's a long-time advertising exec who prevously worked in sales roles at Microsoft and Yahoo and sits on the boards of the Interactive Advertising Bureau and the Ad Council.

Daniel Tejada, Amazon sales manager of digital agency Blue Wheel Media, described Dallaire as "a big picture guy" who helped with both Amazon's search and programmatic ad business. In seven years at Amazon, Dallaire's purview grew from overseeing Amazon's US sales teams to VP of global advertising sales and marketing in 2014. Amazon Advertising's leadership team ladders up Paul Kotas, SVP of Amazon Advertising, one of Amazon's most senior executives.

Business Insider asked execs including Tejada at five advertising agencies that work closely with Amazon who they think is likely to be Dallaire's successor. To be clear, the sources don't have inside knowledge of how Amazon is thinking about filling the role; this list is speculative, based on their knowledge of how the company works and its talent. They said they believed Amazon was looking internally to fill the role and named five internal executives with varying seniority and roles they believed were being considered.

Amazon declined to comment for this story.

The five people named span executives within product and sales roles within Amazon Advertising. They include employees with global and US responsibilities and people on newer teams like agency relationships. They have worked at Amazon for seven to 15 years.

"Amazon likes it that way - they reward loyalty, performance and they're very entrepreneurial," said one agency exec who who spoke anonymously to protect its close relationship with Amazon.

Two agencies said it's not clear that Amazon will replace Dallaire immediately and that it may divvy up his responsibilities among his former colleagues until they fill the role.

Will Margaritis, SVP of e-commerce at Dentsu Aegis Network, another of the five agency execs Business Insider spoke to for this story, said Amazon needs to replace Dallaire's role to keep the momentum around its advertising business going. Amazon is expected to make $11.33 billion from advertising this year, according to research firm eMarketer.

"The biggest holes in Amazon's operation are having someone to tie their products together into a compelling narrative globally, and to have someone that truly understands the needs of the advertising business and how to fight its battles internally," he said. "Amazon is retail-first, and they're often protective to a fault, often hindering their progress. Even beyond a visionary, they need a bulldog to fight for growth internally."

Below are the five Amazon execs sources said are being considered for Dallaire's role, listed alphabetically.

Do you work at Amazon and think we overlooked a key player or ignored someone? Have something else you want to share about Amazon? Email me at ljohnson@businessinsider.com or contact me on Confide or Signal at 720-261-0417.