|Born||September 23, 1959|
|Place of birth||Newark, New Jersey|
|First Film||The Burning (1981)|
Jason Alexander (born Jason Scott Greenspan, September 23, 1959, in Newark, New Jersey), is a television, cinema and musical theatre actor, best known for his role as George Costanza on the hit television series Seinfeld.
Alexander is the son of Alex and Ruth Greenspan. He has a half-sister, Karen Van Horn, and a half-brother, Michael Greenspan. He has been married to Daena E. Title since May 31, 1981. They have two children, Gabriel and Noah.
Alexander is a 1977 graduate of Livingston High School in Livingston, New Jersey. He attended Boston University, but left the summer before his senior year after getting work in New York City. He was later given an honorary degree. 
Alexander was one of the stars of the award-winning television sitcom Seinfeld in which he played the neurotic ne'er-do-well George Costanza, Jerry Seinfeld's best friend. He has also appeared in a number of movies (Love! Valour! Compassion!, Dunston Checks In, and Pretty Woman among them) and did some work as a director, including a recent successful Hollywood concert version of the musical Hair, for which he was also the MC. He is also known for providing the voice of the lead character in the cult animated series Duckman, as well as the voice of Catbert, the evil director of human resources, in the short-lived Dilbert animated series, based on the popular comic strip.
Alexander began his acting career on the New York stage. On Broadway, he appeared in Stephen Sondheim's Merrily We Roll Along, The Rink, Sweeney Todd co-starring with Angela Lansbury for which he has won several awards, Neil Simon's Broadway Bound, Accomplice, and Jerome Robbins' Broadway, for which he was awarded the 1989 Tony Award for Best Actor in a Musical. Alexander has also done a McDonalds commercial advertising the McDLT, in which he sings. He has also appeared in KFC commercials, including one with baseball superstar Barry Bonds of the San Francisco Giants and another one opposite Trista Rehn of The Bachelorette. Though it was rumored (here, among other sources) that he no longer appears in these commercials due to the alleged cruelty to animals by KFC suppliers and slaughterhouses, he settled the controversy in Adweek [August 2, 2006]. Alexander said, "That's PETA bullcrap. I loved working for KFC. I was targeted by PETA to broker something between them. I think KFC really stepped up to the plate; unfortunately PETA did not." He is also featured in country star Brad Paisley's music video, "Celebrity".
In the fall of 2004, he began appearing in a new sitcom on CBS, Listen Up, costarring Malcolm-Jamal Warner. His character was based on sportswriter Tony Kornheiser, but the show did not last the entire season and was not renewed for a second season. He had previously starred in the failed sitcom Bob Patterson (2001) and, years prior to Seinfeld, was featured in the 1984-1985 sitcom E/R.
Alexander continues to appear in live stage shows including in 2005 Barbra Streisand's Memorable, Birthday Party for Stephen Sondheim at the Hollywood Bowl in which he and Angela Lansbury again appeared doing selections again from Sweeney Todd. This appearance was memorable because of the outstanding performance and the ending in which Lansbury tripped over a wire on stage and fell, injuring her leg near the end of the performance.
In the summer of 2005, he appeared with Lee Iacocca in ads for DaimlerChrysler vehicles which is coincidental, considering the fact that his character on Seinfeld, George Costanza, once bought a Chrysler convertible solely on the belief that it was previously owned by Jon Voight (the actual owner was a John Voight, a New York dentist)
In one of his few cinematic appearances, he played another memorable character (aside from Costanza) — an unlikeable womanizer named Mauricio — in the movie Shallow Hal (2001) against Jack Black.
Alexander also appeared with Kelsey Grammer in the musical adaptation of Charles Dickens A Christmas Carol. He played Jacob Marley to Grammer's Ebenezer Scrooge. Alexander also appeared in Rob Reiner's 1994 film North starring Elijah Wood and Bruce Willis along with Julia Louis-Dreyfus, one of his Seinfeld co-stars.
Alexander appears on the Family Guy: Live in Vegas CD singing a verse in the song "All Cartoons are F**kin' Dicks".
He featured in the Friends episode "The One where Rosita dies" as a suicidal supply manager named Earl. Phoebe rings him trying to sell him toner and she learns about his problem and tries to convince him not to commit suicide. This is referred to in an episode of Malcolm in the Middle where Alexander appears as a neurotic and critical loner called Leonard. He describes himself as free and mentions that he makes money with a job "selling toner over the phone", also in the episode, he was repeatedly harassed by a man named George; his character's name on Seinfeld.
Alexander is also the national spokesman for the Scleroderma Foundation, a leading organization dedicated to raising awareness of the disease and assisting those who are afflicted.
He performed a mentalism and magic act at the World Famous Magic Castle in Hollywood, California on April 24–30 2006.
On the June 26, 2006 episode of the Jimmy Kimmel Live talk show, Alexander demonstrated several self-defense techniques. He was also the Host of the 230th July 4, 2006 of the PBS July 4 "A Capitol Fourth" Celebrations in Washington, D.C. in which he sang, danced, and played tuned drums.
Alexander has also appeared several times on Bravo's Celebrity Poker Showdown, and won the final table in the 8th season, finishing ahead of (in order) Robin Tunney, Michael Ian Black, Ida Siconolfi, and Keegan-Michael Key. At one point, Alexander was down to less than $12,000 in chips, when Michael Ian Black imploded, finishing third after having had nearly 80% of the chips on the table. Alexander played for United Way of the greater New Orleans area, and won $500,000 for the charity.
He's also appeared on the popular show "Monk," in the episode Mr. Monk and the Other Detective. Jason played a private detective named Marty Eels who competed with Monk. His character had a history of being a crummy detective, and Monk became suspicious when Eels started solving the crime by somewhat questionable, and in some ways Monkish, means (e.g. figuring out where a car had gone by the bug splatters on its windshield). The Captain pins it down to jealousy and takes him off the case, prompting Monk to question himself instead. However, Monk discovers that Marty already knew all the facts about the case from his mother, who was a phone-call monitorer, and was making it look like he was discovering clues with his own brilliance ("He was cheating!"). In the end of the episode, after Monk rescues Marty's mother, he officially retires (without admitting that "he was cheating!") and takes a job offered to Monk early in the episode, teaching about investigating.
Jason also did the voice of Hugo the Gargoyle from The Hunchback of Notre Dame
On August 6, 2006, Alexander signed on to feature as a regular cast-member in the second season of Everybody Hates Chris.
Alexander was the host of the Comedy Central roast of actor William Shatner on August 13, 2006, first airing August 20, 2006.