His agent, Larry Corsa, confirmed that Morris passed away in Los Angeles on Wednesday at the Barlow Respiratory Hospital, where he had been under care for several weeks, said The Hollywood Reporter.
The actor worked in films like Robin Hardy's 1973 horror "The Wicker Man", in which he played the gravedigger, the sci-fi film "Lifeforce", about space vampires who invade London and Gene Wilder's "The Adventure of Sherlock Holmes' Smarter Brother" (1977).
Morris also appeared in comedy roles in films like "Lisztomania" (1975), Woody Allen's 1975 comedy "Love and Death" and drama-comedy "My Girl 2" with Dan Aykroyd and Jamie Lee Curtis.
His television work included roles on "The Avengers," "Murder, She Wrote", "Deadwood" and most recently, "It's Always Sunny in Philadelphia."
Morris last appeared in the Zach Galifianakis starrer 2008 comedy "Visioneers".