Simmons has his hand in everything-from clothing to debit cards to jewelry to energy drinks-but he'll always be most famous as co-founder of Def Jam, the music label that put hip-hop on the map.

Simmons grew up in Hollis, the "drug trading capital of Queens," and started out in his teens as a hustler and dealer himself but later turned to rap, promoting and managing acts like Kurtis Blow and Run-DMC, the group co-founded by his brother, Reverend Run. In 1984, Simmons teamed up with hirsute music producer Rick Rubin to launch Def Jam. Their first single was "I Need a Beat" by a 16-year-old L.L. Cool J, and the label struck gold with seminal '80s rap acts like the Beastie Boys and Public Enemy. Rubin departed the company in 1989, but Def Jam continued to ride the wave of rap and hip-hop's popularity over the course of the '90s. Simmons cashed out in 1999, selling his outstanding stake in Universal for an estimated $100 million.

Simmons is the original hip-hop multi-tasker, the man who showed the world that you really can make music, produce movies and TV shows, create an energy drink, produce a line of jewelry, stamp your name on a pre-paid debit card, and publish books. Of course, his most famous sideline over the years has been his clothing line, Phat Farm, which he founded in 1992 and expanded in the late '90s with Baby Phat, ex-wife Kimora Lee's line of womenswear. Simmons sold off Phat Farm in 2004 for $140 million and now is primarily a political activist and author. [Image via Getty]