Jay Scott Greenspan, 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.
Known For

The Gettysburg Address
Noah Brooks (voice)
2025
Paddy Chayefsky: Collector of Words
Self
2025

The Electric State
Ted / Wingman
2025

Stealing Pulp Fiction
Dr. Mendelbaum
2024

Dick Van Dyke: 98 Years of Magic
Self - Performer
2023

Leo
Jayda's Dad (voice)
2023

The Conspiracy
2022

Killing Me Softly with His Songs
Self
2022

Out of Office
2022

Cinderella: The Reunion, A Special Edition of 20/20
Self
2022

Dunston Checks Out
Jason Alexander (archival footage)
2022

Broadway: Beyond the Golden Age
Self
2021

The Rocky Horror Musical Live Stream
Narrator
2020

Faith Based
Nicky Steele
2020

My Boyfriend's Meds
Dr. Sternbach
2020

The Portuguese Kid
Barry Dragonetti
2018

Bucky and the Squirrels
Jason Alexander
2018

Broadway: The Next Generation
Self
2017

The Truth Is in the Stars
Self
2017

The Mark Lembeck Technique
Mark Lembeck
2016

Best Worst Thing That Ever Could Have Happened...
Self
2016

For the Love of Spock
Self
2016

There's Something About Romcoms
Self
2016

Tom and Jerry: Back to Oz
Mr. Bibb / The Nome King (voice)
2016

The Last Laugh
Self
2016

China, Il The Musical
Harold
2015

Larry Gaye: Renegade Male Flight Attendant
Larry's Dad
2015

Misery Loves Comedy
Self
2015

Wild Card
Pinky
2015

How Murray Saved Christmas
Doc Holiday (voice)
2014

Lucky Stiff
Vinnie Di Ruzzio
2014

Stars In Shorts
Sid Rosenthal
2012

National Lampoon's Another Dirty Movie
Self (uncredited)
2012
Say It Ain't Solo
Himself
2012

The Voyages of Young Doctor Dolittle
Eugene (voice)
2011

Dora the Explorer: Dora's Enchanted Forest Adventures
Owl (voice)
2011

A Fairly Odd Movie: Grow Up, Timmy Turner!
Cosmo
2011

Not Your Time
Sid Rosenthal
2010

Quantum Quest: A Cassini Space Odyssey
Moronic (voice)
2010

Rock Slyde
Mailman Stan
2010
Meteor
Dr. Chetwyn
2009

Hachi: A Dog's Tale
Carl
2009

Jerry Seinfeld: Submarine Captain
Himself
2007

The Grand
Dr. Yakov Achmed
2007

Farce of the Penguins
Penguin on Belly (voice)
2006

Talkshow with Spike Feresten
(1 episode)
2006

Comedy Central Roast of William Shatner
Self - Roastmaster
2006

How to Go Out on a Date in Queens
Johnny
2006

Snoop Dogg's Hood of Horror
British Record Mogul
2006

Ira & Abby
Dr. Morris Saperstein
2006

Earth to America
self
2005

Everybody Hates Chris
(2 episodes)
2005

The Aristocrats
Self
2005

A Christmas Carol
Jacob Marley / Marley's Ghost
2004

The Seinfeld Story
Self
2004

Seinfeld: How It Began
Self/George Costanza
2004
The Tony Danza Show
Self - Guest · (3 episodes)
2004

The Ellen DeGeneres Show
Self · (2 episodes)
2003

The Very Best of America's Funniest Comedians
Self (archive footage)
2003

101 Dalmatians II: Patch's London Adventure
Lightning (voice)
2003

The Man Who Saved Christmas
A.C. Gilbert
2002

The Hunchback of Notre Dame II
Gargoyle Hugo (voice)
2002

Being 'Shallow Hal'
Self
2001

Shallow Hal
Mauricio
2001

The Trumpet of the Swan
Father (voice)
2001

The Adventures of Rocky & Bullwinkle
Boris
2000

Son of the Beach
(1 episode)
2000

Let's Rap Fire Safety
2000

Ultimate Trek: Star Trek's Greatest Moments
Host
1999

The N.Y. Friars Club Roast of Jerry Stiller
Self - Roastmaster
1999

Larry David: Curb Your Enthusiasm
Self
1999

Love and Action in Chicago
Frank Bonner
1999

Madeline: Lost in Paris
Uncle Horst / Henri (voice)
1999

Sideshow: Alive on the Inside
Narrator
1999

Jingle Bells
Elf (Voice)
1999

Denial
Art Witz
1998

Titey
Titey (voice)
1998

Cinderella
Lionel
1997

Love! Valour! Compassion!
Buzz Hauser
1997

The Hunchback of Notre Dame
Gargoyle Hugo (voice)
1996

Dunston Checks In
Robert Grant
1996
Sex, Censorship and the Silver Screen
Quote Reader
1996

Bye Bye Birdie
Albert J. Peterson
1995

The Last Supper
Anti-Enviroment
1995

For Better or Worse
Michael Makeshift
1995

Blankman
Mr. Stone
1994

North
North's Dad
1994

The Return of Jafar
Abis Mal - the Chief of the Thieves (voice)
1994

Down on the Waterfront
1994

The Paper
Marion Sandusky
1994

Coneheads
Larry Farber
1993

Sexual Healing
Frank
1993

For Goodness Sake
Electronics Store Customer
1993

I Don't Buy Kisses Anymore
Bernie Fishbine
1992

Jacob's Ladder
Geary
1990

White Palace
Neil
1990

Dream On
Randall Townsend · (1 episode)
1990

Pretty Woman
Philip Stuckey
1990

Brighton Beach Memoirs
Pool Player #1
1986

The Mosquito Coast
Hardware Clerk
1986

Rockabye
Lt. Ernest Foy
1986

Senior Trip
Pete
1981

The Sisters Rosensweig
Mervyn

Leo 2

Y llegaron de noche
Carl Laemmle · (7 episodes)
2024

Rock, Paper, Scissors
Jonathan Fartjoke (voice) · (1 episode)
2024

History of the World: Part II
Maurice Cheeks · (1 episode)
2023

Star Trek: Prodigy
Doctor Noum (voice) · (7 episodes)
2021

Star Trek: Prodigy
Counselor Noum (voice) · (16 episodes)
2021

The Problem with Jon Stewart
Jeff Bezos · (1 episode)
2021

History of the Sitcom
Self - Actor · (8 episodes)
2021

Celebrity Wheel of Fortune
Self - Contestant · (1 episode)
2021

Stars in the House
Self · (1 episode)
2020

Stars in the House
Self - Special Guest · (1 episode)
2020

The Movies That Made Us
Self · (1 episode)
2019

Harley Quinn
Sy Borgman (voice) · (13 episodes)
2019

Mad About You
Jason Alexander · (1 episode)
2019

The Conners
Pastor Phil · (2 episodes)
2018

Hit the Road
Ken Swallow · (10 episodes)
2017

Young Sheldon
Gene Lundy · (5 episodes)
2017

The Orville
Olix · (2 episodes)
2017

Kody Kapow
Goji (voice) · (22 episodes)
2017

The Marvelous Mrs. Maisel
Asher Friedman · (1 episode)
2017

Dinner with Dad
Jason Alexander · (8 episodes)
2017

The $100,000 Pyramid
Self · (1 episode)
2016

Match Game
Self - Panelist · (6 episodes)
2016

To Tell the Truth
Self - Panelist · (2 episodes)
2016

The Grinder
Cliff Bemis · (4 episodes)
2015

Big Time in Hollywood, Fl
Jason Alexander · (1 episode)
2015

The Late Late Show with James Corden
Self · (1 episode)
2015

Penn Zero: Part-Time Hero
Coach Wallace (voice) · (1 episode)
2014

The Tom and Jerry Show
Rick (voice) · (52 episodes)
2014

TripTank
Doctor (voice) · (1 episode)
2014

Late Night with Seth Meyers
Self · (1 episode)
2014

Kirstie
Stanford Temple · (1 episode)
2013

Hollywood Game Night
Self · (2 episodes)
2013

Drunk History
William Tweed · (1 episode)
2013

Comedians in Cars Getting Coffee
Self · (1 episode)
2012

Comedy Bang! Bang!
Inspector Gantlet · (1 episode)
2012

Talking Dead
Self · (1 episode)
2011

China, IL
Harold (voice) · (10 episodes)
2011

Harry's Law
Richard Cross · (1 episode)
2011

Fish Hooks
Mr. Nibbles · (0 episode)
2010

Fish Hooks
Mr. Nibbles (voice) · (3 episodes)
2010
The Marriage Ref
Self - Panelist · (1 episode)
2010

The Cleveland Show
(1 episode)
2009

Community
Mountain Man · (1 episode)
2009

Meteor
Dr. Chetwyn · (2 episodes)
2009

Shatner's Raw Nerve
Self · (1 episode)
2008
Step It Up and Dance
(1 episode)
2008

Thank God You're Here
Self · (1 episode)
2007

Rachael Ray
Self - Guest · (1 episode)
2006
Where My Dogs At?
(1 episode)
2006

The New Adventures of Old Christine
Dr. Palmer · (1 episode)
2006

Criminal Minds
Prof. Rothchild · (1 episode)
2005

Robot Chicken
Krampus (voice) · (1 episode)
2005

American Dad!
Mr. Orlando (voice) · (1 episode)
2005

American Dad!
Sal (voice) · (1 episode)
2005

The Late Late Show with Craig Ferguson
Self · (1 episode)
2005

Listen Up!
Tony Kleinman · (22 episodes)
2004

Two and a Half Men
Dr. Goodman · (1 episode)
2003

Real Time with Bill Maher
Self · (8 episodes)
2003

Jimmy Kimmel Live!
(1 episode)
2003

The Twilight Zone
Patient · (1 episode)
2002

Monk
Marty Eels · (1 episode)
2002

Bob Patterson
Bob Patterson · (10 episodes)
2001
Good Day Live
Self · (1 episode)
2001

The Legend of Tarzan
Zutho (voice) · (1 episode)
2001

Primetime Glick
(1 episode)
2001

Critics Choice Awards
Self · (1 episode)
2001

Disney's House of Mouse
(0 episode)
2001

Curb Your Enthusiasm
Jason Alexander · (5 episodes)
2000

The Huntress
(1 episode)
2000

Malcolm in the Middle
Leonard · (1 episode)
2000

The Late Late Show with Craig Kilborn
Self - Guest · (1 episode)
1999

Dilbert
Catbert (voice) · (9 episodes)
1999

Hollywood Squares
Self - Panelist · (10 episodes)
1998

Hollywood Squares
(5 episodes)
1998

Hercules
Poseidon · (0 episode)
1998

Hercules
Poseidon (voice) · (5 episodes)
1998

Muppets Tonight
Self · (2 episodes)
1996

Remember WENN
Alan Ballinger · (1 episode)
1996

Star Trek: Voyager
Kurros · (1 episode)
1995

A Tribute to Stephen Sondheim
1995

Friends
Earl · (1 episode)
1994

Duckman
Duckman (voice) · (70 episodes)
1994

Aladdin
Abis Mal (voice) · (10 episodes)
1994

Aladdin
Captain Albatross (voice) · (1 episode)
1994

Aladdin
Abis Mal / Abnor Mal (voice) · (1 episode)
1994

The Larry Sanders Show
Jason Alexander · (1 episode)
1992

Dinosaurs
Grown Baby (voice) · (1 episode)
1991

Dinosaurs
Stu (voice) · (1 episode)
1991

Dinosaurs
Gus Molehill (voice) · (1 episode)
1991

Dinosaurs
The Job Wizard (voice) · (1 episode)
1991

Dinosaurs
General H. Norman Conquest (voice) · (1 episode)
1991

Dinosaurs
Sexual Harris (voice) · (1 episode)
1991

Dinosaurs
UFO! Host / Announcer (voice) · (1 episode)
1991

The Simpsons
Bourbon Verlander (voice) · (1 episode)
1989

Seinfeld
George Costanza · (180 episodes)
1989

Favorite Son
Chris Van Allen · (3 episodes)
1988

LIVE with Kelly and Mark
Self - Guest · (1 episode)
1988

Everything's Relative
Julian Beeby · (10 episodes)
1987

E/R
Harold Stickley · (6 episodes)
1984

E/R
(1 episode)
1984

Reading Rainbow
Himself - Narrator (voice) · (1 episode)
1983

Newhart
(1 episode)
1982

Late Night with David Letterman
Self · (1 episode)
1982

The Burning
Dave
1981

A Capitol Fourth
Self · (44 episodes)
1980

Saturday Night Live
Self - Host · (1 episode)
1975

Saturday Night Live
Self - Cameo (uncredited) · (1 episode)
1975

Tony Awards
Self - Presenter · (1 episode)
1956

The Emmy Awards
Self · (1 episode)
1949

Saturday TV Funhouse
Titey (voice) · (1 episode)