Fans of Vito Corleone and Jake LaMotta can thank one of the world’s most popular actors for leaving high school before his 17th birthday. The two-time Oscar winner studied his craft at Lee Strasberg’s Actor’s Studio and the Stella Adler Conservatory. De Niro learned a thing or two about business along the way, too: His financial portfolio includes film studio TriBeCa Productions and a handful of posh New York eateries.

Vidal Sassoon

After spending seven years in an orphanage, the future British hair guru struck out, at age 14, for a barbering apprenticeship, followed by a stint in the Israeli Defense Force. Best known for his severe geometric cuts, the coiffure connoisseur is credited for Mia Farrow’s heavily copied ‘do in Rosemary’s Baby. Sassoon’s personal fortune has been valued at roughly $130 million.

Francois Pinault

With holdings like Christie’s Auction House, Gucci, Samsonite and Puma, it’s hard to believe the third-richest man in France quit high school in 1947 to work at his father’s lumber mill. One reason he quit school: Classmates made fun of his poor background. Poetic justice: At last count, the retail kingpin and father-in-law to actress Salma Hayek has amassed an $8.7 billion fortune.

50 Cent

Curtis James Jackson III, aka multi-platinum rapper 50 Cent, made his entrepreneurial debut at age 12, hustling crack on the streets of South Jamaica, Queens. (He earned his GED while doing time for drug possession.) After his attorney slipped them a demo tape, Eminem and Dr. Dre signed Jackson to their label for $1 million. Good move: Jackson’s albums have sold more than 26 million copies. Product endorsements include Reebok sneakers, Vitamin Water and Right Guard body spray. Fifty’s film company Cheetah Vision landed $200 million in funding in 2010.

Jessica Simpson

Southern songstress, fashion designer and reality TV star Jessica Simpson boasts two multi-platinum albums, a shoe line, hair care products and a handful of endorsements–all despite having dropped out of high school. The buxom blonde donned daisy dukes for her 2005 film debut in the Dukes of Hazard and globe-trotted for reality show The Price of Beauty in early 2010. Simpson announced in November she was headed to the altar with one-time NFL tight end Eric Johnson.

Billy Joel

“If I’m not going to Columbia University, I’m going to Columbia Records and you don’t need a high school diploma over there,” Billy Joel once famously declared after learning he had fallen one credit short of his high school graduation requirement in 1967. The six-time Grammy Award winner has sold more than 150 million records worldwide and recently finished touring with Elton John in March 2010. (Joel’s old high school finally agreed to award their famous alumnus a diploma–25 years after he left.) Joel was inducted into the Rock and Roll Hall of Fame in 1999. His estimated net worth is $160 million.

Catherine Zeta-Jones

The daughter of a seamstress and factory owner quit school at age 15 to pursue a stage career in London. The smoldering Welsh actress rose to fame in the late ’90s with her performance alongside Anthony Hopkins and Antonio Banderas in The Mask of Zorro. In 2002 she captivated audiences as Velma Kelly in the blockbuster musical Chicago, earning the actress an Oscar, BAFTA Award and Screen Actors Guild Award. Zeta-Jones also has appeared in advertisements for Elizabeth Arden, T-Mobile, Alfa Romeo and Di Modolo jewelery. Zeta-Jones’s estimated net worth is nearly $45 million.

Richard Carmona

If this former U.S Surgeon General is any example, you can be anything you want to be if you set your mind to it–high school dropouts included. In 1967 Carmona quit Dewitt Clinton High School at age 16 and enlisted in the U.S. Army, where he eventually earned his GED. Carmona graduated at the top of his medical program at University of California, San Francisco in 1979. President George W. Bush appointed Carmona Surgeon General of the United States in 2002.

David Karp

This 24-year-old home-schooled social media visionary has the blogosphere to thank for his millions. The peach-fuzzed creator of popular blogging platform Tumblr dropped out of Bronx Science High School at 15 to establish his own Web development company. As of March 2010 Tumblr gets 2 million posts and averages 15,000 new users per day.

Sidney Poitier

The first black man to win an Academy Award (for Best Actor in 1963) dropped out of school at age 12 to help support his impoverished family. After serving briefly in the U.S. Army, Poitier earned a living as a dishwasher; at 17, he got on as a janitor in exchange for acting classes at the American Negro Theater in New York City. Since 1997 Poitier has served as Bahamian ambassador to Japan. In 2009 he was awarded the Presidential Medal of Freedom by President Obama.

Jay-Z (Shawn Carter)

Jay-Z may have “99 problems,” but not having a high school diploma ain’t one. Carter grew up in one of Brooklyn’s roughest housing projects, dealing drugs before finding salvation in hip hop. In 1995 Carter took his first single to Def Jam Records, the company he ended up running from 2004 until 2007. In 2008 he signed a 10-year, $150 million deal with Live Nation that gave him control over his records, tours and endorsement deals with companies like Dell and Budweiser. The 10-time Grammy Award-winning hip-hop superstar is now worth an estimated $450 million.

Carl Lindner

This billionaire dropped out of high school to deliver milk for his family’s dairy. In 1940 he used a $1,200 loan to open an ice cream shop with his sister and two brothers. In 1959 he left the business and started investing in savings and loans, and eventually insurance concerns, which he assembled under American Financial Group. In 1984 Lindner bought Chiquita Brands International (formerly United Foods) and ran it until 2001. The family dairy, called United Dairy Farmers, now has 200 ice cream parlors and convenience stores. Lindner’s estimated net worth: $1.7 billion.

Simon Cowell

The caustic judge pulled down an estimated $80 million last year, thanks to his involvement with American Idol;Britain’s Got Talent; musical talent show The X Factor; and SyCo records, his production company. The 50-year-old impresario dropped out of school at age 16 and landed a job in the mailroom at EMI. At 23 he left to start his own record label, Fanfare. Cowell recently shifted his focus to a U.S. version of the The X Factor, where he serves as both judge and executive producer.

Gisele Bundchen

When Bundchen was 14 years old a modeling scout discovered her in a Brazilian shopping mall. In 1996 she debuted at Fashion Week in New York City. The highest paid model in the world is worth about $150 million, thanks to contracts with Versace, Dior and other companies. She also has a line of sandals called Ipanema by Gisele.

Richard Branson

The son of a barrister and a flight attendant dropped out of Stowe School at age 16 to start an arts and culture magazine called Student. In 1970 at age 20 he founded a mail-order record retailer called Virgin. He later opened a record shop and recording studio, which became retail chain Virgin Records and record company Virgin Music. His Virgin Group empire now includes 200 companies in 30 countries, spanning airlines, music festivals, mobile companies and other businesses. Today Branson owns two private Caribbean islands, Necker and Mosquito, and has an estimated net worth of $4 billion.