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->''"The greatest part of the job was... that was for nine years it was a pleasure to go to work."''
-->--'''Jason Alexander''', summing up his time on ''Seinfeld''

Jay Scott Greenspan (born September 23, 1959), otherwise known as [[StageName Jason Alexander]], is an American actor known to the world as the one and only George Costanza from ''Series/{{Seinfeld}}''.

In actuality, the man is an accomplished performer on the stage, having won a Tony Award for his singing contributions. However, it would be his role as George Costanza, {{Jerkass}} extraordinaire and [[HeterosexualLifePartners best]] [[NotThatTheresAnythingWrongWithThat friend]] to main character Jerry Seinfeld that would make Alexander a true household name. Being named "the greatest sitcom character of all time" by none other than Creator/RickyGervais, Alexander's accolades for the role included Emmy and Golden Globe nominations, as well as a win at the Screen Actors Guild Awards. One could say that, along with Michael Richards as Kramer, he became a BreakoutCharacter on the show.

His son Gabriel Greenspan is also an accomplished actor.

He's also an expert poker player.
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!!Filmography:
!!!Film:
* ''Film/TheBurning'' (1981) as Dave
* ''Film/TheMosquitoCoast'' (1986) as a Clerk
* ''Film/PrettyWoman'' (1990) as Philip Stuckey
* ''Film/JacobsLadder'' (1990) as Geary
* ''Film/{{Coneheads}}'' (1993) as Larry Farber
* ''WesternAnimation/AladdinTheReturnOfJafar'' (1994) as the voice of Abis Mal
* ''Film/{{North}}'' (1994) as North's father
* ''Film/DunstonChecksIn'' (1996) as the dad and hotel manager
* ''WesternAnimation/{{The Hunchback of Notre Dame|Disney}}'' (1996) as the voice of Hugo
* ''Film/LoveValourCompassion'' (1997) as Buzz Hauser
* ''Film/ShallowHal'' (2001) as Mauricio Wilson
* ''Film/FarceOfThePenguins'' (2007) as Penguin on Belly
* ''Film/AFairlyOddMovieGrowUpTimmyTurner'' (2011) as Cosmo (TV Movie)

!!!TV:
* ''Series/EverythingsRelative1987'' as Julian Beeby
* ''Series/{{Seinfeld}}'' (1990-1998) as George Costanza
* ''WesternAnimation/AladdinTheSeries'' (1994-1995) as the voice of Abis Mal
* ''WesternAnimation/{{Duckman}}'' (1994-1997) as the voice of Duckman
* ''Series/StarTrekVoyager'', "[[Recap/StarTrekVoyagerS5E19ThinkTank Think Tank]]", (1999), as Kurros
* ''WesternAnimation/{{Dilbert}}'' (1999-2000) as the voice of Catbert
* ''Series/CurbYourEnthusiasm'' (2001, 2009) as himself
* ''Listen Up'' (2004-2005) as Tony Kleinman
* ''Series/EverybodyHatesChris'' (2006-2007) as Principal Edwards
* ''Series/YoungSheldon'' (2018, 2020-) as Gene Lundy
* ''WesternAnimation/HarleyQuinn2019'' (2019-2020) as Sy Borgman
* ''[[WesternAnimation/RockPaperScissorsNickelodeon Rock, Paper, Scissors]]'' (2024) as Jonathan Fartjoke

!!!Theatre:
* ''Theatre/MerrilyWeRollAlong'' (1981) as Joe
* ''Jerome Robbins' Broadway'' (1989) as the narrator - Tony Award for Best Actor in a Musical
* ''Theatre/TheProducers'' (2003 Los Angeles production) as Max Bialystock
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!!Tropes associated with Jason Alexander include:
* TheCastShowOff: He's a former Tony-winning Broadway actor with a great singing voice and occasionally shows it off. Inverted in Seinfeld, where for George's answering machine message where he was told to sing offkey and had to do some retakes before properly singing the song crappily enough.
* TwoFirstNames: His StageName, Jason Alexander.
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