A look back at some of our most famous (and infamous) 40 Under 40 listees when they were fresh-faced and new to the spotlight.
Jeff Bezos, CEO, Amazon
List debut: 1999
Bezos was No. 2 on Fortune’s inaugural 40 Under 40 list in 1999, when the ranking was based solely on wealth. At the time, Bezos told us he carried these four gadgets everywhere: a vibrating email pager, a cell phone, a digital camera, and a Swiss Army knife. He was 35 and already worth $5.74 billion.
Mark Zuckerberg, CEO, Facebook
List debut: 2009
Zuckerberg first appeared on the 40 Under 40 list in 2009 (after the list relaunched in its current format). His Fortune magazine debut came earlier, though, in 2005 when he was 21 and still carried business cards that said “I’m CEO … bitch.” At the time, he told us, “I’m in this to build something cool, not to get bought.”
Elon Musk
List debut: 2002
Now an electric-car magnate, Musk first made Fortune’s list of 40 luminaries in 2002, after PayPal, a company he had a hand in getting off the ground with his startup X.com, went public. He was 31 and founded SpaceX the same year. Tesla wouldn’t come along until the year after that.
See the full 40 Under 40 2017 list.
Ivanka Trump
List debut: 2014
Years before anyone thought her father had real political ambitions, the poised 32-year-old landed on Fortune’s list. At the time, she was the face of a successful fashion line, and had just spearheaded the deal to redevelop the Old Post Office in Washington, D.C., into a Trump hotel.
Michael Dell
List debut: 1999
The original entrepreneur to hold the top 40 Under 40 spot, Dell, a college dropout, started tech giant Dell Computer from his dorm room. At 34, he was the richest person on our debut ranking by far—with a net worth of $21.5 billion. He would go on to make many (many) more appearances on the list.
Elizabeth Holmes
List debut: 2014
In one of the most spectacular business flameouts in decades, Holmes’s blood-testing startup flew high (Holmes made the list when she was 31 with a company valued at $9 billion), but came crashing down to earth over questions about its technology. Now, Holmes is trying to rebuild it, albeit on a much smaller scale.
A version of this article appears as part of our 40 Under 40 list in the Sept. 1, 2017 issue of Fortune with the headline "We Knew Them When."