Freaks and Geeks
Debuted in 1999, teen dramedy Freaks and Geeks launched the careers of several of its leading cast, including Linda Cardellini, Busy Phillips, James Franco, Seth Rogen, and Jason Segel, and even executive producer Judd Apatow (of The Cable Guy, Bridesmaids, The 40-Year-Old Virgin, Knocked Up, Superbad, Talladega Nights, Forgetting Sarah Marshall, Step Brothers, and Anchorman fame).