Clemenson was born and raised in Humboldt, Iowa, the son of drug store owners Ruth Alzora (Dayton) and Ernest Arnold Clemenson.[1] In his early teens, he delivered the Des Moines Register, which had a long tradition of awarding scholarships to top East Coast preparatory schools to a select few "paper boys."[6] Clemenson, a straight-A junior high school student, won a Register scholarship to Phillips Academy in Andover, Massachusetts.[7]
He participated in many theatrical productions at Phillips Academy.
In 1973, while Clemenson was enrolled at Phillips, his father died at age 58.[8]
Upon graduation from Phillips in 1976, he entered Harvard College. From his freshman year onward he received important roles in campus stage productions. When Clemenson starred in a Harvard Lampoon sketch comedy show, a Harvard Crimson theater critic described Clemenson as "hugely talented actor who can trigger hysteria with any of a dozen subtle expressions or inflections."[9] Other Crimson critics described his performances in Shakespeare plays as "a tour de force of sheer talent and intelligence" (in The Winter's Tale)[10] and "a very fine and subtle performance" (in Measure for Measure).[11] He displayed early on his remarkable range when he undertook with inimitable flair and hilarious effect the hugely solemn role of Erde "the green-faced torso", goddess of the Earth, in Peter Sellars's Loeb Drama Center puppet production of Wagner's Ring cycle (1979).[citation needed][12]
During many summers he would return to Humboldt to star in, and later direct, local community theater plays at Humboldt's Castle Theatre.[2]
In 1999, Clemenson appeared in the Buffy the Vampire Slayer episode "Bad Girls" as a grotesquely obese demon named Balthazar. He wore a large padded suit and extensive make-up for the role, and the character's repulsive, villainous nature contradicted many of his earlier roles.
Clemenson became well-known for his role as Jerry "Hands" Espenson on the television series Boston Legal. For playing Espenson, he won an Emmy Award for Best Guest Actor in a Drama Series in 2006 and was nominated for the same award in 2007.[5] He remained with the series through to its finale in 2008.
In 2009, Clemenson joined CSI: Miami as the new medical examiner, Dr. Tom Loman. He appeared throughout the show's eighth, ninth, and tenth seasons as a recurring character. In 2013, he appeared as a guest star in Harry's Law.
