The American actor died due to complications from gall stones, choosing not to remove them owing to his age, reported Deadline.
Molinaro made his television debut with "Get Smart". He played Agent 44 for two episodes.
Immediately after that, he played Officer Murray Greshler on "The Odd Couple", appearing in 73 episodes.
Then came his most celebrated role of Al Delvecchioin in season four of "Happy Days".
"The Odd Couple" star also appeared in two films, 1976's "Freaky Friday" and 1980's "The Great American Traffic Jam".
Born in Kenosha, Wisconsin, Molinaro also appeared in "Punky Brewster" and "Step by Step."
Molinaro is survived by his wife Betty and his son Michael.