Michael Richards

For years, this wacky, manic comic actor was beloved for his indelible portrayal of Kramer, the high-strung next-door neighbor to the title character on Seinfeld. During his nine seasons on the legendary sitcom, this formerly little-known performer became a recognizable star and won three Emmys. Unfortunately, Richards' post-sitcom career stalled from the get-go, with a short-lived, eponymous series and then nothing until November 2006, when he had an on-stage, racially charged breakdown that was caught on video and subsequently disseminated over the Internet. While performing a stand-up routine at The Laugh Factory in Los Angeles, Richards became enraged when a couple of African-American audience members began heckling him. He responded by verbally attacking them, repeating the N-word several times, until they  and most of the other patrons  began leaving the club. Ultimately, Richards stormed off the stage, but by then the damage had been done. Despite a quick apology on Late Night with David Letterman, Richards had irreparably damaged his already tarnished reputation and devastated myriad Seinfeld fans who worried that they could no longer enjoy the sitcom the way they once had.