A former comic, Thomerson has amassed credits in over 30 films and made over 50 TV appearances since the mid-1970s. Making his feature debut in the 1976 comedy "Car Wash", Thomerson went on to appear in some worthier projects including Robert Altman's "A Wedding", Alan Rudolph's "Remember My Name" (1978) and Clint Eastwood's "Honkytonk Man" (1982). In 1985, Thomerson teamed with thrifty auteur Charles Band to star as Jack Deth in the futuristic thriller "Trancers". They reteamed for the sequels "Trancers II: The Return of Jack Deth" (1991), "Trancers III: Deth Lives" (1992) and "Trancer 4: Jack of Swords" (1994). Thomerson has also starred in other straight-to-video Band classics including "Dollman" (1991) and "Dollman vs. Demonic Toys" (1993).
Between films Thomerson worked as a series regular on several ill-fated shows including the Bill Cosby variety series "Cos" (1976); "Angie" (1979-80); "Glory Years" (1987); "Down and Out in Beverly Hills" (1987) and "Sirens" (1993). His numerous TV guest spots include "Hunter", "St. Elsewhere", "21 Jump Street" and "Major Dad".