40 under 40: Hall of Fame by Leigh Gallagher @FortuneMagazine September 24, 2015, 8:42 AM EDT E-mail Tweet Facebook Linkedin Share icons The 2015 40 Under 40 class is a mighty impressive group, but we haven’t forgotten some of their legendary peers. There are no repeats on our list this year, which is why there are some household names you don’t see (hello, Zuck). Instead, we’ve created our first-ever Hall of Fame: these are the alumni of the 40 Under 40 (its current format, 2009–2015) who most embody the spirit of the list. 1 Mark Zuckerberg, 31, Co-Founder and CEO, Facebook FB Photograph by David Ramos — Getty Images There’s a reason the creator of the Social Network—you know the one—has been in the top five of our list every year since we brought it back in 2009. In a dorm room at Harvard he created a social tool that would become globally ubiquitous; now it’s an ad powerhouse too. Does anyone know anyone who doesn’t know what Facebook is? 2 Larry Page, 42, Sergey Brin, 42, Co-founders, Google GOOG Larry Page, left and Sergey Brin.Photographs by AP/Corbis What is there to say about Google that isn’t already obvious every time you use a computer? You likely use Google in ways you don’t even think about—search, chat, videoconferencing—and it has ambitions well beyond all that, like curing cancer, free Wi-Fi everywhere, and increasing human longevity. 3 Elon Musk, 44, CEO, Tesla TSLA , CEO and CTO, SpaceX Photograph by Mike Blake — Reuters Talk about ambition. Co-founding the first major online-payments platform wasn’t enough, so he created a rocket-launching company. Then he made electric vehicles sexy. Now he wants to help people travel through a high-speed tube from L.A. to San Francisco. His life is a science-fiction film. 4 Marc Andreessen, 44, Co-founder and General Partner, Andreessen Horowitz Photograph by Michael Kovac — Getty Images for Vanity Fair The founder of the venture capital firm Andreessen Horowitz is such a revered investor it’s easy to forget he’s also one of the fathers of the Internet as the co-author of Mosaic and co-founder of Netscape. His ability to see around corners and handpick a success is the stuff of Silicon Valley legend. 5 Kevin Plank, 43, Founder and CEO, Under Armour Photograph by Katie Kramer — CNBC/NBCU Photo Bank via Getty Images Many small sports-apparel players have tried to take on Nike. Kevin Plank succeeded. His is the ultimate entrepreneur story: He created a wicking undershirt while he was still a college football player to solve his own problem—then grew it into a sports-apparel juggernaut with nearly $4 billion in revenues. 6 Marissa Mayer, 40, CEO, Yahoo YHOO Photograph by Mike Pont — Getty Images When Mayer first made this list, it was because she was one of the most senior women at Google. Then she took a high-risk leap to go run Yahoo, a company whose future was uncertain. In the process she became one of the most influential female CEOs on the planet. 7 Biz Stone, 41, Evan Williams, 43, Jack Dorsey, 38, Co-founders, Twitter TWTR Jack Dorsey, Biz Stone and Evan Williams.Photograph by Richard Drew — AP When they created a mobile-SMS platform for posting a brief status, they had no idea it would become a go-to place for news. Twitter may have its challenges, but it has become central in driving the global conversation, and it isn’t going away. 8 Meredith Whitney, 45, Financial Analyst Photograph by Patrick T. Fallon — Bloomberg via Getty Images She has since wound down her research firm and shut a nascent hedge fund, but when Whitney made a bold call in 2007 that Citigroup would need to cut its dividend, it shook the entire financial world and cemented her reputation as a Wall Street Nostradamus. 9 Travis Kalanick, 39, Co-founder and CEO, Uber Photograph by Robert Schlesinger — picture-alliance/dpa/AP His tactics may look brutal to some, but Kalanick single-handedly disrupted the old-school taxi industry and created a new one—app-enabled ride hailing—which has exploded. As Uber has gotten bigger—and more controversial—Kalanick has only amped up his unapologetic approach. 10 Brian Chesky, 34, Joe Gebbia, 34, Nate Blecharczyk, 32, Co-founders, Airbnb Co-founders, Joe Gebbia, CPO, left, Nathan Blecharczyk, CTO and Brian Chesky, CEO.Courtesy of AirBnb The website these three originally created to cater to couch surfers quickly became a pioneer of the “sharing economy.” Then it became a disrupter of the hotel industry. Now it’s a platform for 40 million people in 34,000 cities with a $25 billion valuation. Chesky is CEO; Gebbia, chief product officer; Blecharczyk, CTO. 11 Elizabeth Holmes, 31, Founder and CEO, Theranos Photograph by Joe Pugliese for Fortune Her revolutionary blood analytics company can perform 70 different tests from a single pinprick. Its star-studded board—which includes Henry Kissinger—believes Theranos can get much bigger. Its $9 billion valuation supports that. 12 Daniel Ek, 32, Spotify Photograph by Taylor Hill — FilmMagic/Getty Images He took on the music industry early on with a streaming service from Sweden; now Apple is getting into the same game. 13 Gary Vaynerchuk, 39, Vaynermedia Photograph by Stephen Lovekin — Getty Images This self-made entrepreneur became the go-to guru on all things social media marketing—and he’s done it with a brash, bold style that earned him his share of critics along with hundreds of thousands of fans. As he says himself in a promotional video for his YouTube channel, “You may know me from wine, or writing books, or the cover of magazines, or cursing on stage.” 14 Tracy Britt Cool, 31, Berkshire Hathaway brk.a Photograph by Daniel Acker — Bloomberg via Getty Images Warren Buffett trusts this young protégé so much he put her in charge of one Berkshire company and on the board of four. “She thinks like I would,” he has said. 15 David Chang, 38, Momofuku Restaurant Group Photograph by Lester Cohen — Getty Images for WIRED Chang may look like an unusual pick—but he’s an unusual chef. His cult noodle shop became a pork-bun empire. Along the way, he’s grown up from controversial ramen rebel to controversial corporate leader and mega-influencer in the food world. 16 Matteo Renzi, 40, Prime Minister, Italy Photograph by Kenzo Tribouillard — AFP/Getty Images The youngest Prime Minister in Italy’s history rode a tide of optimism into office and shook up the ruling class. 17 Jonathan Gray, 45, Blackstone Photograph by Victor J. Blue — Bloomberg via Getty Images We put the private equity firm’s real estate chief on our list in 2009; he’s said to be the heir apparent to CEO Steve Schwarzman. A version of this article appears in the October 1, 2015 issue of Fortune magazine with the headline “40 Under 40’s Greatest Hits.” To see this year’s 40 Under 40 list, visit fortune.com/40-under-40.