Blossom died Friday of natural causes at a nursing home in Santa Monica, said his daughter, Deborah.
Blossom starred in the 1974 cult horror movie "Deranged," in which he played a demented farmer who digs up his domineering mother's corpse and takes it home — then digs up other bodies to keep her company before he begins hunting live victims.
But he's best known in films as a character actor whose credits include "The Hospital," "Slaughterhouse-Five," "The Great Gatsby," "Close Encounters of the Third Kind," "Escape From Alcatraz," "Resurrection" and "Doc Hollywood."
Then there was his role as "old man Marley" in the 1990 family comedy "Home Alone."
"That's certainly the one he gained the most recognition from, and people still remember him from that," said Deborah Blossom. "He was very happy with the outcome of that movie and its popularity, and he was very happy to be recognized for it."
With a laugh, she added: "I think he'd rather be recognized for that than 'Deranged.' "
Blossom also did a lot of television, with guest roles on series such as "Moonlighting," "Northern Exposure" and "In the Heat of the Night."
In the late '70s, he won a Soapy Award as best villain for a recurring role in the soap opera "Another World."
Blossom was also a poet, whose works were published in several books.
"He wrote every day for 60 years," his daughter said. "I always say about him: He's a poet who made a living as an actor. His poetry was all pretty much about his philosophy: How can humans come together and unite?"
That's reflected in the 2000 documentary "Full Blossom: The Life of Poet/Actor Roberts Blossom," directed by James Brih Abee.
Born March 25, 1924, in New Haven, Conn., Blossom grew up in Cleveland, where his family lost most of its fortune in the 1929 stock market crash. (Roberts is a family name on his mother's side.)
A 1941 graduate of Asheville School in North Carolina, Blossom attended Harvard for a year before being drafted into the Army during World War II. After the war, he began acting in Cleveland.
In New York in the '60s, he formed Filmstage, which has been described as a seminal multimedia avant-garde theater troupe. He retired from acting in the late '90s.
Blossom's marriage to his first wife, Beverly, ended in divorce. His second wife, Marylin, died in 1982.
Besides his daughter, he is survived by a son, Michael.