'Seinfeld' debuted on NBC in 1989 and ran for nine seasons, becoming one of America's most beloved sitcoms -- created by Larry David and starring Jerry Seinfeld as a fictional version of himself, the show centered around the stand-up comedian, three of his neurotic friends, and the everyday situations and relationships that drove them nuts. 'Seinfeld' has endured in syndication on various TV networks, where new and old fans can relive and discover classic episodes every week. It's hard to believe it's been 15 years since the show took its final bow -- and to celebrate the anniversary of the end of one of the greatest sitcoms of all time, we're taking a look back at your favorite cast members to see what they're up to now.

Jerry Seinfeld, Himself

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Then: Jerry Seinfeld played a fictional version of himself, a moderately famous New York stand-up comedian who is the most sane of his group of friends, although he's still pretty neurotic and a total neat-freak.

Now: Seinfeld has appeared on '30 Rock' and Larry David's 'Curb Your Enthusiasm' and continues to perform stand-up. He's also the creator and host of the web series 'Comedians in Cars Getting Coffee.'

Jason Alexander, George Costanza

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Then: Jason Alexander played George Costanza, Jerry's insecure best friend who is often very petty and dishonest. Alexander based his portrayal of George in part off of Woody Allen, which is why he chose to wear glasses -- in real life, Alexander doesn't need them. Other actors considered for the role included Danny DeVito, David Alan Grier, and Nathan Lane.

Now: Alexander has guest-starred on 'Two and a Half Men,' 'Mike and Molly,' and a very memorable musical episode of 'Community.' He's also lent his voice talents to 'American Dad' and Adult Swim's 'China, IL.'

Julia Louis-Dreyfus, Elaine Benes

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Then: Julia Louis-Dreyfus' Elaine wasn't originally written into the series and didn't appear in the first episode. The feisty and assertive Elaine is Jerry's ex, and is based on Carol Leifer, a friend of Seinfeld's who dated him in real life. Rosie O'Donnell, Megan Mullally, Mariska Hargitay, and Patricia Heaton all auditioned for the part.

Now: Louis-Dreyfus currently stars on the HBO series 'Veep' as Vice President Selina Meyer. She also recently appeared in the indie film 'Enough Said,' which co-starred James Gandolfini in one of his final roles.

Michael Richards, Cosmo Kramer

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Then: Michael Richards played Cosmo Kramer, Jerry's wacky neighbor from across the hall who always enters Jerry's apartment wildly and without knocking. The character was based on a neighbor of Larry David's named Kenny Kramer; 'Monk' star Tony Shalhoub was also considered for the role.

Now: Richards had a voice part in Seinfeld's animated film 'Bee Movie' in 2007, and participated in the multi-episode 'Seinfeld' reunion on Larry David's 'Curb Your Enthusiasm.' He currently stars on Kirstie Alley's new sitcom 'Kirstie' on TV Land.

Wayne Knight, Newman

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Then: Wayne Knight played Newman, a fellow tenant and mailman in Jerry and Kramer's building and Jerry's nemesis, whom Jerry always greets with a sinister "Hello, Newman." Knight had previously appeared in 'Dirty Dancing' and 'Born on the Fourth of July,' and made his debut on 'Seinfeld' in 1992.

Now: You may also recognize Knight from roles in 'Jurassic Park' and '3rd Rock from the Sun.' Currently he stars on the sitcom 'The Exes,' and has lent his voice to animated projects like 'Kung Fu Panda' and 'Regular Show.'

Jerry Stiller, Frank Costanza

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Then: Jerry Stiller played George Costanza's highly-excitable and eccentric father, Frank, replacing previous actor, John Randolph. Stiller is also the father of actor Ben Stiller.

Now: After 'Seinfeld,' Stiller starred on the sitcom 'The King of Queens,' and has appeared in his son's films 'Zoolander' and 'The Heartbreak Kid.'

Estelle Harris, Estelle Costanza

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Then: Estelle Harris played Estelle, George's very dramatic mother who often argues with both her husband and son. Harris had previously appeared on 'Night Court' and 'Married with Children.'

Now: Harris is the voice of Mrs. Potatohead in the 'Toy Story' films and shorts, and played Muriel on the Disney channel's 'Suite Life of Zack and Cody.'

Heidi Swedberg, Susan Ross


Then: Heidi Swedberg played Susan, George's on-again, off-again girlfriend who eventually dies of licking toxic wedding invitation envelopes during their engagement.

Now: After making guest appearances for years on shows like 'ER' and 'Gilmore Girls,' Swedberg's main focus now is her music. She's been playing the ukulele since she was a child, and performs with the band Heidi Swedberg and the Sukey Jump Band. Her most recent acting gig was a 2010 guest spot on the series 'Hawthorne.'

John O'Hurley, Jacopo Peterman

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Then: John O'Hurley played Jacopo Peterman, founder of the J. Peterman company and Elaine's boss for a period of time -- he fires her at one point when she tests positive for opium due to eating poppy seed muffins. Peterman is based on real-life catalog and retail entrepreneur John Peterman.

Now: O'Hurley lends his considerable voice talents to shows like 'Phineas and Ferb,' 'The Looney Tunes Show,' and 'Scooby-Doo! Mystery Incorporated.' He's hosted the National Dog Show since 2002 and is a regular 'Game Show America' host.