After training at London's Royal Academy of Dramatic Art and honing his skills in Canadian theater and TV, Vernon made his US film debut in John Boorman's noir/gangster classic, "Point Blank" (1967) as a trusted friend who betrays Lee Marvin. He again failed to inspire confidence as the ineffectual mayor of San Francisco in "Dirty Harry" and the comparable Mayor Flambo in the TV spoof "Sledge Hammer!" (ABC, 1988). Vernon may be best remembered as the sinister Dean Wormer in John Landis' "Animal House" (1978), a role he reprised for the TV spin-off "Delta House" (ABC, 1979). This led to more film comedy roles, a highlight being Mr. Big in the blaxploitation spoof "I'm Gonna Git You Sucka" (1988), and a generation later his "Animal House" cachet resulted in tribute-minded guest roles in films such as "Sorority Boys" (2002).
Vernon has also been in many TV-movies and guested on scored of popular primetime and syndicated series--including a season as Mr. Smith on the syndicated action series "Acapulco H.E.A.T." from 1993 to 1994--as well as having a lucrative second career as a voice actor on several animated series, including "The Fantastic Four," "The Incredible Hulk," "Pinky & the Brain," "Spider-Man" and as crime boss Rupert Thorne on "Batman."