Founders: Vinod Khosla, Scott McNealy, Andy Bechtolsheim, and Bill Joy
Named after the Stanford University Network, Sun Microsystems became the goliath of computer workstations in the 1990s, so much so it once used the slogan, "We're the dot in dot-com." But the end of the dotcom boom meant the shuttering of many businesses that relied on Sun's technologies; the company ultimately was acquired by Oracle for nearly $7.3 billion. Its co-founders, all household names in tech, have had rich second acts. Kholsa became a general partner at Kleiner Perkins before starting his own venture firm, Khosla Ventures. Joy and Bechtolsheim are investors (Bechtolsheim was one of the earliest backers of Google), and McNealy co-founded social-media polling company Wayin.
Founders: Marc Andreessen, James H. Clark
Credit Andreessen and Clark for shaping the modern-day web surfing experience. In 1994, they released Mosaic Netscape, or Netscape Navigator, the first widely distributed Internet browser. Netscape was acquired by AOL in 1999 for $10 billion. Clark went on to start Healtheon, which later merged with WebMD (wbmd), and he was the star of Michael Lewis's The New New Thing, a book about Silicon Valley. Andreessen is co-founder of Andreessen Horowitz and one of the Valley's most sought-after advisers.
General Motors Company
Founders: William Durant, Charles Stewart Mott
One of the largest automakers in the world started little more than a century ago with just the Buick brand in its portfolio. Ironically, Durant, a leading manufacturer of horse-drawn carriages then, was dubious of early automobiles and their safety but saw a potential market for improved models and invested aggressively. By 1910, General Motors (gm) had either acquired or started Oldsmobile, Cadillac, and Chevrolet and eventually became so successful it led global auto sales for 70 years until 2008.
Founders: Bill Gates, Paul Allen
Personal computing arguably wouldn't be the force it is today without Bill Gates and Paul Allen, childhood friends who founded Microsoft (msft) in 1975 after writing a programming language for the Altair 8800 microcomputer. Although Allen would depart eight years later, alleging Gates tried to dilute his equity, their work together has yielded important PC software like Windows, the dominant desktop operating system, even to this day. Allen keeps his hand in technology though his investing arm, Vulcan Capital. Gates, who established the Bill and Melinda Gates Foundation and works with Warren Buffett to encourage philanthropy, earlier this year said he would step up his role at Microsoft at the request of new CEO Satya Nadella.
Founders: Elon Musk, Peter Thiel, Max Levchin, Luke Nosek, and Ken Howery
Musk, Thiel, Levchin, Nosek, and Howery launched the Internet-based payment service in 1998, which rapidly expanded after users made it their payment method of choice on eBay (ebay). No surprise then that eBay acquired the startup for $1.5 billion, which proved a wise move, as PayPal remains the fastest-growing business inside the company. Meanwhile, there's a reason early PayPal alum earned the name "PayPal mafia": Musk, for one, dreamed up and runs Tesla (tsla), the disruptive electronic car company, while Thiel largely became a startup investor, channeling funds into businesses like Facebook.
Founders: Yves Guillemot, Claude Guillemot, Michel Guillemot, Gérard Guillemot, and Christian Guillemot
In 1986, the Guillemot brothers established this videogame publisher from a small village in France. Inking deals with distributors like Electronic Arts (ea), Ubisoft soon expanded beyond its native country to the U.S. and U.K. Now Ubisoft has 29 development studios across 19 countries and ranks third behind Activision Blizzard and EA as the third-largest independent games publisher in the world, with popular franchises like Just Dance, Prince of Persia, and Assassin's Creed. All five brothers remain involved with Ubisoft on an everyday basis. For instance, Yves remains as CEO, and Claude serves as executive vice president of operations.
Founders: Mark Zuckerberg, Dustin Moskovitz, Eduardo Saverin, Andrew McCollum, and Chris Hughes
Over 1 billion global users have Zuckerberg and crew to thank for redefining friendship in the digital age. The product of a Harvard version of Hot or Not in 2004, "The Facebook," as it was then called, captured users keen on a new web solution for keeping tabs on and communicating with classmates, friends, and eventually, family. So much so that Facebook (fb) is the second-most popular Internet site in the world. Friction among the founders became the basis of an Oscar-winning movie; in reality the founders have used their wealth to fund other projects. Hughes bought The New Republic magazine; Moskowitz founded Asana, a management software company; McCollom is an entrepreneur in residence; and Saverin, who renounced his U.S. citizenship, invests in startups.
Founders: Jack Dorsey, Evan Williams, Biz Stone, and Noah Glass
In Twitter's (twtr) case, less is definitely more. But even Dorsey, Williams, Stone, and Glass were probably caught off-guard by the success of their startup, which popularized 140-character messages updated in real time and served as an important communication tool in moments of crisis, like the Egyptian protests in 2011. Dorsey, who also serves as CEO of Square, is chairman, and Williams, who has a new startup called Medium, is on the board of directors. Stone has a new book out, titled, charmingly, Things a Little Bird Taught Me.
Founders: Henry Luce, Briton Hadden
Yale classmates Luce and Haden quit their jobs at the Baltimore News in 1922 to develop TIME magazine, the first publication in what eventually became a stable of nearly 130 magazines, spanning fashion and pop culture to sports. Luce remained editor-in-chief of all Time Inc.'s titles until his retirement in 1964. Hadden died at the age of 31. Luce once said of his partnership with Hadden: "Somehow, despite the greatest differences in temperaments and even in interests, we had to work together. We were an organization. At the center of our lives -- our job, our function -- at that point everything we had belonged to each other." (Time Inc., which is to be spun out of Time Warner (twx) later this year, publishes Fortune.)
Founders: Larry Page, Sergey Brin
Google's (goog) remains the quintessential Silicon Valley tale. Founded by Ph.D. students Page and Brin in a Stanford dorm room, the tech giant employs over 30,000, developing disparate-seeming products from online advertising tools -- the lion's share of revenues -- to self-driving cars. To launch the company the pair handed the CEO reins to Eric Schmidt (now chairman), but Page, who had served as president of product, in 2011 became chief executive. Brin runs the company's futuristic research lab Google X.