Kelly suffered congestive heart failure on Jan. 25 in Greensboro, N.C., his son announced Tuesday.
Along with the adaptation of the Mark Twain novel for which he's best known, Kelly appeared in Gone With the Wind, He Walked By Night, and The West Point Story before retiring from Hollywood at age 25.
Kelly was a veteran of World War II, serving in the Army in Europe. He had a distinguished post-Hollywood career, working as an administrator for the Peace Corps in the African nation of Liberia and as an international relations advisor for the Department of Agriculture.
Survivors include his wife of 67 years, Susie; his children Ann, Matt, Eileen, Kevin, Mark and Paul; 12 grandchildren; and two great-grandchildren.