In the film, he played Tom Burnett in United 93 as a true 9/11 victim. On television, he appears regularly in The Adventures of Brisco County, Jr., where he plays the role of Socrates Poole. He also had a recurring role in Veronica Mars. Clemenson also appeared in an episode of NCIS season 6, “Dead Reckoning.” He also appeared in two episodes of season 2 of The Mentalist. He also played Jimmy Masterson in the 3rd episode of Memphis Beat, “Love Me Tender”. After graduating from Phillips University in 1976, he entered Harvard College. From his first year of study, he received important roles in theatrical productions on campus. When Clemenson appeared on a Harvard Lampoon sketch comedy, a Harvard Crimson theater critic described Clemenson as “an extremely talented actor who can trigger hysteria with a dozen subtle expressions or inflections.”  Other critics of Crimson have described his performances in Shakespeare`s plays as “a tour de force of sheer talent and intelligence” (in The Winter`s Tale) and “a very fine and subtle performance” (measure for measure).  Early on, he showed his remarkable range when, with an inimitable flair and hilarious effect, he took on the very solemn role of the earth “the green-faced torso” in Peter Sellars` Loeb Drama Center puppet production of Wagner`s Ring cycle (1979). [ref. needed] In 2016, he played Assistant District Attorney William Hodgman in American Crime Story: The People v.
O. J. Simpson. Clemenson starred in the film United 93 as Tom Burnett, one of the victims of the 9/11 hijacking that crashed after a passenger revolt in rural Pennsylvania. He also had a recurring role in Veronica Mars as Abel Koontz. In total, Clemenson appeared in three episodes of the series: “Like a Virgin,” “Mars vs. Mars” and “Rat Saw God”. Clemenson also appeared in an episode of NCIS season 6, “Dead Reckoning.” He also appeared in two episodes of season 2 of The Mentalist. He also played Jimmy Masterson in the 3rd episode of Memphis Beat, “Love Me Tender”. Clemenson began his career in a number of character roles in film and television. He was a law student in the television version of The Paper Chase, English teacher of Alex Keaton in the television series Family Ties, security salesman in The Golden Girls, suspect in season 10, episode 14 of NYPD Blue, bailiff in the film Legal Eagles by Ivan Reitman, flight doctor in the film Apollo 13, cop in The Big Lebowski, murderer in The Fisher King and Dr. Dale Lawrence in the movie And the Band Played On.
He had a regular role as Socrates Poole, a lawyer in the Wild West, in the Fox series The Adventures of Brisco County, Jr. For many summers he returned to Humboldt to perform in local community plays at Humboldt`s Castle Theatre and later to direct.  The percentage of approved Tomatometer critics who gave this film a positive rating. In 1999, Clemenson appeared in the episode “Bad Girls” of Buffy the Vampire Slayer as a grotesquely obese demon named Balthazar. He wore a large padded suit and full makeup for the role, and the character`s disgusting and nasty nature contradicted many of his previous roles. Many of Clemenson`s early film and television roles matched his personality as a bright and quiet professional. He was a law student in the television version of The Paper Chase, an English teacher for Alex Keaton in the TV series Family Ties, a bailiff in Ivan Reitman`s Legal Eagles, a flight doctor in the Apollo 13 movie, a cop in The Big Lebowski, a murderer in The Fisher King and Dr. Dale Lawrence in the film And the Band Played On. Although he has been a familiar face for over a decade, his name wasn`t as well known until recently. After graduating from Harvard College in 1980 and the Yale School of Drama in 1984, he moved to Los Angeles.  Clemenson and his Boston Legal star James Spader are old friends from the Phillips Academy era. Christian Dayton Clemenson (born March 17, 1958) is an American actor. is an American actor.
He is best known for his portrayal of Jerry “Hands” Espenson in the television series Boston Legal, for which he was nominated for three Emmy Awards and won the 2006 Emmy Award for Outstanding Guest Actor in a Drama Series. He has appeared in a number of highly acclaimed films, including Hannah and Her Sisters, Broadcast News, Apollo 13 and The Big Lebowski, and portrayed Tom Burnett in Paul Greengrass` United 93. He starred in The People v. O. J. Simpson: American Crime Story as District Attorney William Hodgman. Clemenson is best known for his role as Jerry “Hands” Espenson on the television series Boston Legal. For his role as Espenson, he won an Emmy Award for Outstanding Guest Actor in a Drama Series in 2006 and was nominated for the same award in 2007. He remained with the series until the 2008 final. Christian Clemenson (born March 17, 1958)  is an American actor. He is best known for his portrayal of Jerry “Hands” Espenson in the television series Boston Legal, for which he won the 2006 Emmy Award for Outstanding Guest Actor in a Drama Series. He appeared in a tense scene with Holly Hunter in the 1987 film Broadcast News as newsroom editor, “Bobby, Bobby, Bobby… Clemenson was born and raised in Humboldt, Iowa, the son of pharmacy owners Ruth Alzora (Dayton) and Ernest Arnold Clemenson.
In his early teens, he provided the Des Moines Register, which had a long tradition of awarding scholarships to a few “paper boys” selected from the best preparatory schools on the East Coast.  Clemenson, a high school student, won a Register scholarship to Phillips Academy in Andover, Massachusetts. In 1973, while Clemenson was enrolled in Phillips, his father died at the age of 58. He appeared in numerous theatrical productions at Phillips Academy. .