(written from a Production point of view)
Jason Alexander (born 23 September 1959; age 55) is an American television, film, and stage actor. In 1999, he appeared on Star Trek: Voyager, playing Kurros in the episode "Think Tank". His costume was sold off on the It's A Wrap! sale and auction on eBay and also worn by background actor Patrick Barnitt. 
Alexander is best known for his Emmy Award and Golden Globe-nominated role as George Costanza on the 1990s sitcom Seinfeld. He played the role throughout all nine seasons of the show, from 1990 through 1998. Numerous Trek performers - including, in recurring roles, fellow Voyager guest star Estelle Harris as his overbearing mother, TNG and Voyager guest star Richard Herd as his boss with the New York Yankees, and DS9 guest star Heidi Swedberg as his ill-fated fiancee - appeared on the show during its run, and Harris, Teri Hatcher, Brian George and Phil Morris all reprised earlier roles on the series finale.
Born Jason Scott Greenspan in Newark, New Jersey, Alexander attended that state's Livingston High School before departing before his senior year. It was while attending Livingston that he adopted Jason Alexander as his stage name. He then attended Boston University, but dropped out prior to his senior year after finding work in New York City. The university later awarded him with an honorary degree.
Soon after beginning his acting career on New York stage, Alexander made his feature film debut in the 1981 horror movie The Burning. He then acquired his first steady TV work when he joined the cast of the short-lived medical sitcom E/R, from 1984 through 1985. He briefly became the star of his own series, Everything's Relative, in 1987. He made infrequent appearances in film and on television throughout the 1980s, while at the same time continuing his career on the Broadway stage, including the lead role in Jerome Robbins' Broadway, which garnered Alexander the 1989 Tony Award for Best Performance by a Leading Actor in a Musical.
Alexander played the rotten Philip Stuckey in the hit 1990 romantic comedy Pretty Woman. While Seinfeld was on the airwaves, Alexander had roles in such films as Jacob's Ladder (1990), Coneheads (1993, with fellow Voyager guest star Michael McKean), Ron Howard's The Paper (1994, co-starring Clint Howard), North (1994, featuring Keone Young, Rosalind Chao, and Robert Costanzo), and The Last Supper (1995, with Ron Perlman). He then starred in the 1996 family comedy Dunston Checks In (featuring Frank Kopyc and Paula Malcomson) and made his feature directorial debut with the film For Better or Worse, also released in 1996, in which Alexander also starred along with Star Trek: The Next Generation guest actor Robert Costanzo. And, in 1997, he starred with John Glover in Love! Valour! Compassion!, based on the Terrence McNally play.
Besides Seinfeld, Alexander was also nominated for an Emmy Award for his guest appearance in a 1993 episode of the HBO series Dream On. This episode, entitled "Oral Sex, Lies and Videotape", also guest-starred Iman and Michael McKean.
Alexander was heard as the voice of Hugo the gargoyle in Disney's 1996 animated film The Hunchback of Notre Dame, a role he reprised in the 2002 direct-to-video sequel and the cartoon series House of Mouse. (Tony Jay, David Ogden Stiers, and Frank Welker also voiced characters in the first film.) Alexander had previously voiced bungling thief Abis Mal in Disney's direct-to-video release of The Return of Jafar and, subsequently, on the Aladdin TV series. Additionally, from 1994 through 1997, Alexander voiced the title role in the Emmy nominated series Duckman: Private Dick/Family Man. He more recently supplied the voice of the evil Catbert in the short-lived, comic-strip based animated series Dilbert.
Alexander's recent film credits include The Adventures of Rocky & Bullwinkle (2000, co-starring Max Grodénchik, Norman Lloyd, Steve Rankin, and Whoopi Goldberg) and Shallow Hal (2001, with Bruce McGill). He also made appearances on such TV shows as Friends, Malcolm in the Middle, and Monk (with Stanley Kamel) and starred in the short-lived sitcoms Bob Patterson and Listen Up.
An admittedly avid Star Trek fan since childhood, Alexander is such an expert on Star Trek: The Original Series that he passed a Star Trek knowledge test on the Howard Stern program. Alexander portrayed a parody of Captain James T. Kirk in a TV special entitled Ultimate Trek: Star Trek's Greatest Moments. He went on to act with the man who originated the role of Kirk, William Shatner, in an episode of Bob Patterson (on which Alexander starred in the title role). Alexander also hosted The Comedy Central Roast of William Shatner with Andy Dick, Nichelle Nichols and George Takei on the dais to join in the roast, Clint Howard portraying and adult version of Balok and Jeri Ryan in the audience, and both have appeared in the Brad Paisley music videos "Celebrity" and "Online".
Alexander again worked with Shatner on the computer-animated film Quantum Quest, in which he and Shatner have voice-over roles. Also lending their voices to this project are fellow Star Trek alumni Robert Picardo, Chris Pine, and Brent Spiner. 
Other Trek connections
- Favorite Son (1988 mini-series) with Ronny Cox, Richard Herd, and Brian Thompson
- Seinfeld 11 episodes (1995 - 1998) with Richard Herd
- I Don't Buy Kisses Anymore (1993 film) with Robert DoQui
- Bye Bye Birdie (1995 TV movie) with Vanessa Williams
- The Nanny episode "The Tart with Heart" (1996) with Daniel Davis
- Duckman episode "Where No Duckman Has Gone Before" (1997) with James Doohan, Marina Sirtis and Leonard Nimoy
Franklin & Bash starring Malcolm McDowell
Alexander has contributed twice to this hit legal comedy. First guest-starring in the first season "Big Fish"(2011) with Geoffrey Blake, Patrick Fischler and Freda Foh Shen. Alexander returned in the second season this time as director helming "Last Dance" with Anne Elizabeth Ramsay and Todd Stashwick.