Christopher's agent Robert Malcom said the actor died Saturday at his home in Pasadena, California. He told the Associated Press that Christopher's wife said her husband died peacefully.
Malcom said Christopher was diagnosed with cancer more than a year ago and had been in hospice since the beginning of the week.
He is survived by his wife, Barbara, and his two sons.
Christopher is best known for the role of Father Francis Mulcahy on "M.A.S.H.," the 1970s TV show set during the Korean War.
"Everyone adored him," fellow "M.A.S.H." actor Loretta Swit, said. "A great sense of humor and a great humanitarian. He became TV's quintessential padre as Father Mulcahy on 'M.A.S.H.'
"It was the most perfect casting ever known."