At 20 years old, Bill Gates dropped out to start Microsoft with his childhood friend Paul Allen.
Attended Harvard: 1973-1975
The applied math major was known at Harvard for his intense study habits. Gates would go on a 36-hour study-bender, sleep for 10 hours, socialize, then start from the beginning. He would even audit classes that were the same time frame as his scheduled classes.
Gates left the university because he and Allen wanted to be the first to establish the software industry.
The Microsoft mogul has long hovered at or near the top of the list of wealthiest people in the world, worth approximately $81 billion. Gates recently stepped down as chairman of Microsoft and now serves as a technology adviser for the company.
Gates and his wife, Melinda, started the Bill and Melinda Gates Foundation, through which they have donated more than $30 billion to charities around the world.
Matt Damon dropped out one semester and 12 credits shy of a degree.
Attended Harvard: 1988-1992
The Boston-born actor was known to cut class to attend auditions during his time at Harvard.
Damon, an English major, dropped out of the Ivy his senior year after earning a spot in the film "Geronimo: An American Legend."
However it wasn't until 1997 that Damon received his big break starring in "Good Will Hunting," which earned the actor an Academy Award.
His career has since taken off, making his net worth approximately $75 million. The actor/producer is also heavily involved in humanitarian work; Damon is one of the founders of Water.org.
Mark Zuckerberg built the world's largest social network, Facebook, in his dorm room.
Attended Harvard: 2002-2004
On Feb. 4, 2004, Zuckerberg launched the first version of Facebook from his Harvard dorm, and he is now worth approximately $35 billion.
Zuckerberg dropped out shortly after Facebook's launch and moved to Palo Alto, California, to continue to develop the site.
Facebook went public in 2012 for the fourth-biggest IPO ever (and biggest in tech) at $16 billion.
Poet Robert Frost also attended Dartmouth, but he never earned a formal college degree.
Attended Harvard: 1897-1899
After leaving Dartmouth, Frost enrolled at Harvard to study liberal arts. But he soon left the university to support his family, working jobs as a teacher, cobbler, and farmer.
Frost later said of his time at Harvard: "They could not make a student of me here, but they gave it their best."
In 1912, Frost and his wife moved to England, where he was inspired by contemporary British poets. When he returned to the US a few years later, he was the most famous poet in the country. Two years before his death, Frost read his poem "The Gift Outright" at President John F. Kennedy's inauguration.
Alexa Von Tobel left Harvard Business School to build LearnVest, a personal finance website.
Attended Harvard: 2002-2006 A.B. in Psychology, 2008-2009 HBS
Von Tobel graduated Magna Cum Laude Plus from Harvard College, where she was the first student to write a thesis on Bhutan. But she didn't make it through graduate school at Harvard Business School.
Von Tobel had been developing LearnVest, a startup that helps people with financial planning, since college, and once her company started gaining recognition, she left HBS to build her company.
LearnVest, valued at about $100 million, is now one of the most important personal finance companies. President Barack Obama named Von Tobel one of the first members of the Presidential Ambassadors for Global Entrepreneurship for her work with LearnVest.
Composer Cole Porter dropped out of Harvard Law School to pursue his passion for music.
Attended Harvard: 1913-1914
With the encouragement of the dean of the law school, Porter dropped out and joined Harvard's musical faculty, studying harmony and counterpoint.
Porter later became one of the most famous composers and musicians in American history. Some of his most famous shows are "Anything Goes" and "Kiss me Kate," which won the first ever Tony Award for Best Musical.
Facebook's third employee, Dustin Moskovitz, is now worth $8.3 billion.
Attended Harvard: 2002-2004
Moskovitz moved to Palo Alto in June 2004 with fellow Facebook founders Mark Zuckerberg and Chris Hughes. While at Facebook he served as the chief technology officer and vice president of engineering.
He left Facebook in 2008 to start the software company Asana but maintains a 2.34% share in Facebook.
Moskovitz and his wife started Good Ventures, which gives millions of dollars toward causes all over the world.
William Randolph Hearst could not graduate with his 1885 class because he was expelled for throwing parties and pulling pranks on his professors.
Attended Harvard: 1881-expelled before 1885
Newspaper and magazine magnate William Randolph Hearst was quite the troublemaker while at Harvard. The prankster once sneaked a donkey into his professor's room, leaving a note saying, "Now there are two of you."
However the prank that led to Hearst's dismissal was when he sent his professors chamber pots with their names inscribed in the bottom. It also didn't help that he was harboring an alligator named Champagne Charlie in his dorm room.
After his expulsion, Hearst went on to build the nation's largest newspaper chain and was a key influencer of American journalism. Aside from the newspaper business, he served two terms in the US House of Representatives. The main character of Orson Welles' film "Citizen Kane" is based on Hearst.
Shortly after dropping out, Bonnie Raitt signed a record deal with Warner Bros.
Attended Harvard: 1967-1970
While at the Ivy, Bonnie Raitt studied social relations and African studies, and she became very involved in the culturally rich music and political scenes of 1960s Cambridge.
"I couldn't wait to get back to where there were folkies and the antiwar and civil rights movements," she said of her time at Harvard. "There were so many great music and political scenes going on in the late '60s in Cambridge."
But three years after entering college, she left Harvard to pursue her music career full time. Soon after that, she released her first album.
Raitt has released 19 albums over the past 40-plus years and won 10 Grammys. Rolling Stone awarded Raitt as 50th on its list of the "100 Greatest Singers Of All Time." She has continued to be involved in nonprofits all over the world, specifically involving social justice, human rights, and music education.
Buckminster "Bucky" Fuller was expelled not once but twice for excessively socializing and missing his exams.
Attended Harvard: 1913-1915
The inventor, designer, and author was the second president of Mensa and racked up 25 patents in his career. He is best known for inventing the "synergetic geometric" geodesic dome, with over 300,000 domes built all over the world.
Out of five generations of his family attending the Ivy, Bucky was the first not to earn a degree. He was rejected by Harvard's social clubs, so he often blew off class to go to Broadway shows. Harvard expelled Fuller for skipping class and spending all of his tuition money in New York.
Later, Harvard even had the "excessive socializer" return to teach some classes at the university.
Pete Seeger's passion for folk music took priority over his studies, causing him to lose his scholarship and drop out.
Attended Harvard: 1937-1938
Seeger left Harvard after the university denied him financial aid because of his low grades and, he said, his left-wing politics.
After leaving Harvard, Seeger joined the band The Weavers and focused on his music and political activism. Seeger was the leader of the folk revival of the 1950s and inspired many of today's musicians including Bruce Springsteen.
Seeger and Springsteen even paired up to perform "This Land is Your Land" at Obama's 2009 inauguration.
In 2009, Seeger said his purpose was "to show folks there's a lot of good music in this world, and if used right, it may help to save the planet."
Edwin H. Land studied chemistry for one year. His experiments with polarizing light led him to invent the Polaroid camera.
Attended Harvard: 1927-1928
As a freshman at Harvard, Land was a chemistry major and experimented with polarizing light.
He left Harvard to continue his experiments in New York, where he would sneak into Columbia University to use its labs. He also became a regular at the New York City Public Library, which led to his first invention: a polarizing film.
Land later founded the Polaroid Corporation and invented the Polaroid camera, the first camera to take and develop a picture in under a minute.
Land returned to Harvard, where he and a former physics professor established the Land-Wheelwright Laboratories, but he left again in 1932 without earning a degree. The university awarded him an honorary doctorate in 1957.
James Blake played on the Harvard team for two seasons before pursuing a professional tennis career.
Attended Harvard: 1999-2001
While at Harvard, Blake was a member of the super-exclusive A.D. club, one of Harvard's nine famed final clubs, a type of social club.
When Blake left Harvard after his sophomore year, he was the No. 1-rated college tennis player in the country.
After leaving the Ivy, Blake went on to win 10 major titles, compete in 24 major finals, and represent the US in the Beijing Olympics, where he was a semi-finalist. His highest career ranking for singles was No. 4 in the world.
