Jason Alexander (born September 23, 1959) is an American actor, comedian 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.
Alexander was born Jason Scott Greenspan in Newark, New Jersey, the son of Jewish parents Ruth Minnie (née Simon), a nurse and health care administrator, and Alexander B. Greenspan, an accounting manager. He has a half-sister, Karen Van Horn, and a half-brother, Michael Greenspan. Alexander is a 1977 graduate of Livingston High School in Livingston, New Jersey. Alexander had a very wheezy voice growing up, primarily because of his asthma. 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 in 1995. He is a talented magician, and only switched to acting as a career when he realized that he was unlikely to succeed as a magician.
Alexander began his acting career on the New York stage and is an accomplished singer and dancer. On Broadway, he appeared in Stephen Sondheim's Merrily We Roll Along, Kander & Ebb's The Rink, Neil Simon's Broadway Bound, Accomplice, and Jerome Robbins' Broadway, for which he garnered the 1989 Tony Award for Best Actor in a Musical. Returning to the stage in 2003, Alexander was cast in a successful run, opposite Martin Short, in the Los Angeles production of Mel Brooks' The Producers. Alexander also appeared with Kelsey Grammer in the 2004 musical adaptation of Charles Dickens' A Christmas Carol. He played Jacob Marley to Grammer's Ebenezer Scrooge.