He is better known when a striking actor, virtually all famously for his role as Willy Loman around Arthur Miller's Death of a Salesman and in the successful Cocoon (1985) though he has acted in many comedies, including a Chris Farley/David Spade movie Tommy Boy. He is too known for his role within F/X and F/X 2.

In stager, Dennehy mass produced his Broadway debut inside 1995 & in 1999 was a foremost male actor to exist as voted a Sarah Siddons Award for his work inside Chicago theatre.

Dennehy joined a United States Marines in 1959 and served until 1963. Around 1989, he became one of many Veteran(s) with Disputed Status when he told the New York Times that he claimed that he received shrapnel woundeds in the Vietnam War. Inside 1993, he told Playboy that he served five years within Vietnam. Still, his single overseas tour was to Okinawa. He apologized for his faithlessly claims around 1999.

When you took a 1980s, Dennehy gradually became the valuable supporting streaming video player around mainstream films & later gained leading human status in the kinky thriller Best Seller where he appeared alongside James Woods to memorable effect. He gained his arthouse spurs in a period of the equivalent month whenever he starred in the Peter Greenaway movie The Belly of an Architect. Commenting upon this unusual venture, Dennehy said, "I've been in a lot of movies but this is the first film I've made."

Fallowing his extraordinary TV performance when John Wayne Gacy in the chilling TV mini-series To Catch A Killer, Dennehy seemed to withdraw into the world of TV Movies, including many backpacking when unorthodox fuzz Jack Reed. But, his brobdingnagian profits around 1996 playing Willy Loman indicated that he wwhen as right an actor inside stage as he experienced been in moving picture.

He was parodied in the South Park movie: see image.