Jay Scott Greenspan (born September 23, 1959), better known by his professional name of Jason Alexander, is an American actor, writer, comedian, television director and producer, and singer. He is best known for his role as George Costanza on the television series Seinfeld, appearing in the sitcom from 1989 to 1998. He also has had an active career on the stage, appearing in several Broadway musicals including Jerome Robbins' Broadway in 1989, for which he won the Tony Award as Best Actor in a Musical. He appeared in the Los Angeles production of The Producers with Martin Short. He is the Artistic Director of "Reprise! Broadway's Best in Los Angeles," where he has directed several musicals. Alexander is also an avid poker player.

Filmography

• 2026Jimmy — Louis B. Mayer
• Mating Season — Alan (voice)
• 2026To Kill a Nazi — Narrator
• LEGO Marvel Avengers: Strange Tails — Magneto (voice)
• 2025Stealing Pulp Fiction — Dr. Mendelbaum
• The Bad Guys: The Series — Mysterious Figure (voice), D.B. Cougar (voice)
• 2025The Electric State — Ted / Wingman
• 2025The Gettysburg Address — Noah Brooks (voice)
• Rock, Paper, Scissors — Jonathan Fartjoke (voice)
• Y llegaron de noche — Carl Laemmle
• History of the World: Part II — Maurice Cheeks
• 2023Leo — Jayda's Dad (voice)
• 2022Dunston Checks Out — Jason Alexander (archival footage)
• 2022Out of Office
• 2022The Conspiracy
• Star Trek: Prodigy — Doctor Noum (voice), Counselor Noum (voice)
• The Problem with Jon Stewart — Jeff Bezos
• 2020Faith Based — Nicky Steele
• 2020My Boyfriend's Meds — Dr. Sternbach
• 2020The Rocky Horror Musical Live Stream — Narrator
• Harley Quinn — Sy Borgman (voice)
• Mad About You — Jason Alexander
• 2018Bucky and the Squirrels — Jason Alexander
• The Conners — Pastor Phil
• 2018The Portuguese Kid — Barry Dragonetti
• Dinner with Dad — Jason Alexander, Writer
• Hit the Road — Ken Swallow
• Kody Kapow — Goji (voice)
• The Marvelous Mrs. Maisel — Asher Friedman
• The Orville — Olix
• Young Sheldon — Gene Lundy, Director
• 2016The Mark Lembeck Technique — Mark Lembeck, Consulting Producer
• 2016Tom and Jerry: Back to Oz — Mr. Bibb / The Nome King (voice)
• Big Time in Hollywood, Fl — Jason Alexander
• 2015China, Il The Musical — Harold
• 2015Larry Gaye: Renegade Male Flight Attendant — Larry's Dad
• The Grinder — Cliff Bemis
• 2015Wild Card — Pinky
• 2014How Murray Saved Christmas — Doc Holiday (voice)
• 2014Lucky Stiff — Vinnie Di Ruzzio
• Penn Zero: Part-Time Hero — Coach Wallace (voice)
• The Tom and Jerry Show — Rick (voice)
• TripTank — Doctor (voice)
• Drunk History — William Tweed
• Kirstie — Stanford Temple
• Comedy Bang! Bang! — Inspector Gantlet
• 2012Stars in Shorts — Sid Rosenthal
• 2011A Fairly Odd Movie: Grow Up, Timmy Turner! — Cosmo
• China, IL — Harold (voice)
• 2011Dora the Explorer: Dora's Enchanted Forest Adventures — Owl (voice)
• Franklin & Bash — Carter Lang
• Harry's Law — Richard Cross
• 2011The Voyages of Young Doctor Dolittle — Eugene (voice)
• Fish Hooks — Mr. Nibbles, Mr. Nibbles (voice)
• Mike & Molly — Director
• 2010Not Your Time — Sid Rosenthal
• 2010Quantum Quest: A Cassini Space Odyssey — Moronic (voice)
• 2010Rock Slyde — Mailman Stan
• Community — Mountain Man
• 2009Hachi: A Dog's Tale — Carl
• Meteor — Dr. Chetwyn
• The Cleveland Show
• Step It Up and Dance
• 2007The Grand — Dr. Yakov Achmed
• Campus Ladies — Director
• 2006Farce of the Penguins — Penguin on Belly (voice)
• 2006How to Go Out on a Date in Queens — Johnny
• 2006Ira & Abby — Dr. Morris Saperstein
• 2006Snoop Dogg's Hood of Horror — British Record Mogul
• Talkshow with Spike Feresten
• The New Adventures of Old Christine — Dr. Palmer
• Where My Dogs At?
• American Dad! — Mr. Orlando (voice), Sal (voice)
• Criminal Minds — Prof. Rothchild, Director
• Everybody Hates Chris — Principal Edwards, Director
• Robot Chicken — Krampus (voice)
• 2004A Christmas Carol — Jacob Marley / Marley's Ghost
• 2004Agent Cody Banks 2: Destination London — Executive Producer
• Listen Up! — Tony Kleinman
• 2004Seinfeld: How It Began — Self/George Costanza
• 2003101 Dalmatians II: Patch's London Adventure — Lightning (voice)
• 2003Agent Cody Banks — Executive Producer
• Two and a Half Men — Dr. Goodman
• Monk — Marty Eels
• 2002The Hunchback of Notre Dame II — Gargoyle Hugo (voice)
• 2002The Man Who Saved Christmas — A.C. Gilbert
• The Twilight Zone — Patient
• Bob Patterson — Bob Patterson, Executive Producer, Story, Teleplay, Creator
• Disney's House of Mouse
• 2001On Edge — Zamboni Phil
• Primetime Glick
• 2001Shallow Hal — Mauricio Wilson
• The Legend of Tarzan — Zutho (voice)
• 2001The Trumpet of the Swan — Father (voice)
• Curb Your Enthusiasm — Jason Alexander
• 2000Let's Rap Fire Safety
• Malcolm in the Middle — Leonard
• Son of the Beach
• 2000The Adventures of Rocky & Bullwinkle — Boris
• The Huntress
• Dilbert — Catbert (voice)
• 1999Jingle Bells — Elf (Voice)
• 1999Just Looking — Director
• 1999Love and Action in Chicago — Frank Bonner
• 1999Madeline: Lost in Paris — Uncle Horst / Henri (voice)
• 1999Sideshow: Alive on the Inside — Narrator
• 1999Ultimate Trek: Star Trek's Greatest Moments — Host
• 1998Denial — Art Witz
• Hercules — Poseidon, Poseidon (voice)
• 1998Titey — Titey (voice)
• 1997Cinderella — Lionel
• 1997Love! Valour! Compassion! — Buzz Hauser
• 1996Dunston Checks In — Robert Grant
• Remember WENN — Alan Ballinger, Director
• 1996The Hunchback of Notre Dame — Gargoyle Hugo (voice)
• 1996The Making of Disney's The Hunchback of Notre Dame
• 1995A Tribute to Stephen Sondheim
• 1995Bye Bye Birdie — Albert J. Peterson
• 1995For Better or Worse — Michael Makeshift, Director
• Star Trek: Voyager — Kurros
• 1995The Last Supper — Anti-Enviroment
• Aladdin — Abis Mal (voice), Captain Albatross (voice), Abis Mal / Abnor Mal (voice)
• 1994Blankman — Mr. Stone
• 1994Down on the Waterfront
• Duckman — Duckman (voice)
• Friends — Earl
• 1994North — North's Dad
• 1994The Paper — Marion Sandusky
• 1994The Return of Jafar — Abis Mal (voice)
• 1993Coneheads — Larry Farber
• 1993For Goodness Sake — Electronics Store Customer
• 1993Sexual Healing — Frank
• The Nanny — Jack
• 1992I Don't Buy Kisses Anymore — Bernie Fishbine
• The Larry Sanders Show — Jason Alexander
• Dinosaurs — Grown Baby (voice), Stu (voice), Gus Molehill (voice), The Job Wizard (voice), General H. Norman Conquest (voice), Sexual Harris (voice), UFO! Host / Announcer (voice)
• Dream On — Randall Townsend
• 1990Jacob's Ladder — Geary
• 1990Pretty Woman — Philip Stuckey
• 1990White Palace — Neil
• Seinfeld — George Costanza, Director
• The Simpsons — Bourbon Verlander (voice)
• Favorite Son — Chris Van Allen
• Everything's Relative — Julian Beeby
• 1986Brighton Beach Memoirs — Pool Player #1
• 1986Rockabye — Lt. Ernest Foy
• 1986The Mosquito Coast — Hardware Clerk
• E/R — Harold Stickley
• Newhart
• 1981Senior Trip — Pete
• 1981The Burning — Dave
• Saturday Night Live — Self - Host, Titey (voice), Self (uncredited)
• Leo 2
• Saturday TV Funhouse — Titey (voice)
• The Sisters Rosensweig — Mervyn

Appearances as themselves (62)

• 2025Paddy Chayefsky: Collector of Words — Self
• 2023Dick Van Dyke: 98 Years of Magic — Self - Performer
• 2022Cinderella: The Reunion, A Special Edition of 20/20 — Self
• 2022Killing Me Softly with His Songs — Self
• 2021Broadway: Beyond the Golden Age — Self
• Celebrity Wheel of Fortune — Self - Contestant
• History of the Sitcom — Self - Actor
• Stars in the House — Self, Self - Special Guest
• Who Wants to Be a Millionaire — Self - Contestant
• The Movies That Made Us — Self
• 2017The Truth Is in the Stars — Self
• 2016Best Worst Thing That Ever Could Have Happened... — Self
• 2016For the Love of Spock — Self
• Match Game — Self - Panelist
• The $100,000 Pyramid — Self
• 2016The Last Laugh — Self (archive footage) (uncredited)
• 2016There's Something About Romcoms — Self
• To Tell the Truth — Self - Panelist
• 2015Misery Loves Comedy — Self
• The Late Late Show with James Corden — Self
• The Late Show with Stephen Colbert — Self - Guest
• Late Night with Seth Meyers — Self - Guest
• Hollywood Game Night — Self
• Comedians in Cars Getting Coffee — Self
• 2012National Lampoon's Another Dirty Movie — Self (uncredited)
• 2012Say It Ain't Solo — Self
• Talking Dead — Self
• The Marriage Ref — Self - Panelist
• Shatner's Raw Nerve — Self
• 2007Jerry Seinfeld: Submarine Captain — Self
• Thank God You're Here — Self
• 2006Comedy Central Roast of William Shatner — Self - Roastmaster
• Rachael Ray — Self - Guest
• 2005Earth to America — self
• 2005The Aristocrats — Self
• The Late Late Show with Craig Ferguson — Self
• 2004Kramer vs. Kramer: Kenny to Cosmo — Self
• 2004The Seinfeld Story — Self
• The Tony Danza Show — Self - Guest
• Jimmy Kimmel Live! — Self
• Real Time with Bill Maher — Self
• The Ellen DeGeneres Show — Self
• 2003The Very Best of America's Funniest Comedians — Self (archive footage)
• 2001Being 'Shallow Hal' — Self
• 2001Bravo Profiles: Penn and Teller — Self
• Critics Choice Awards — Self
• Good Day Live — Self
• 1999Larry David: Curb Your Enthusiasm — Self
• The Late Late Show with Craig Kilborn — Self - Guest
• 1999The N.Y. Friars Club Roast of Jerry Stiller — Self - Roastmaster
• Hollywood Squares — Self - Panelist
• Muppets Tonight — Self
• LIVE with Kelly and Mark — Self - Guest
• Jeopardy! — Self, Self - Clue Presenter
• Reading Rainbow — Self - Narrator (voice)
• Late Night with David Letterman — Self
• A Capitol Fourth — Self
• People's Choice Awards — Self - Host
• Tony Awards — Self - Presenter
• The Emmy Awards — Self
• Golden Globe Awards — Self - Nominee
• Broadway: The Next Generation — Self