In a comedy world dominated by geeky men, Tina Fey is queen. Saturday Night Live's first female head writer made the transition to cast member in 2000 by hosting "Weekend Update" with Jimmy Fallon and later Amy Poehler. She was still a cast member when she wrote 2004's Mean Girls — arguably the smartest, funniest teen comedy to come out of Hollywood since the John Hughes era. Fey left SNL two years later to work on 30 Rock, a sitcom about an SNL-like show. During the 2008 Presidential election, she earned national attention by skewering Sarah Palin with impressions so spot-on it's hard to remember which one-liners — "I can see Russia from my house!" — were real, and which were introduced by Fey.
Watch a video about the TIME 100 heroes and icons including Tina Fey.