He starred as private detective Loren Visser in Blood Simple (1984), the Coen brothers' first film, for which he won the Independent Spirit Award for Best Male Lead.

(1972), Serpico (1973), The Gambler (1974), Bound for Glory (1976), Slap Shot (1977), Airport '77 (1977), Brubaker (1980), Ordinary People (1980), Reds (1981), Silkwood (1983), Missing in Action (1984), Fletch (1985), Back to School (1986), Raising Arizona (1987), Romeo + Juliet (1996), My Best Friend's Wedding (1997), The Iron Giant (1999), Calvary (2014), and Knives Out (2019).

[5] At Clarkson, Walsh had also dabbled in stage productions, and soon after being encouraged by a faculty advisor, he moved to New York City to study at the American Academy of Dramatic Arts.

[4] According to his manager, Sandy Joseph, "Walsh's tremendous body of work includes 119 feature films and more than 250 television productions.

"[6] Being partially deaf in one ear and with an accent harkening from Vermont made it clear to Walsh: "I wasn't going to do Shaw and Shakespeare and Molière — my speech was simply too bad.

After appearances in the films Midnight Cowboy (1969),[1] Alice's Restaurant (1969),[1][2] Little Big Man (1970), Escape from the Planet of the Apes (1971), They Might Be Giants (1971),[2] What's Up, Doc?

(1972),[2] Serpico (1973),[2] The Gambler (1974), Bound for Glory (1976), and Airport '77 (1977),[7] Walsh came to prominence in the iconic 1977 hockey comedy film Slap Shot, in which he played the cynical small town sportswriter Dickie Dunn,[1][2][9] and the 1978 crime film Straight Time, in which he played a vicious parole officer opposite Dustin Hoffman.

[4] Critic Nicolas Rapold called Walsh "a consummate old pro of the second-banana business", while Roger Ebert hailed him as "the poet of sleaze".

[4] Ebert also fabricated his "Stanton-Walsh Rule": "No movie featuring either Harry Dean Stanton or M. Emmet Walsh in a supporting role can be altogether bad.

"[11] Walsh died of cardiac arrest at Northwestern Medical Center in St. Albans, Vermont, on March 19, 2024, three days before his 89th birthday.