httpss://www.youtube.com/watch?v=AiR0yDUgRuw

EXCLUSIVE. “Psycho” star John Gavin – who appeared in several other classics such as “Midnight Lace” and was the US Ambassador to Mexico under Ronald Reagan – has died.

John – who played Sam Loomis in the classic horror flick – died Friday morning … TMZ has learned.

We’re told he succumbed to complications from pneumonia and had battled leukemia for a long time.

John was first hospitalized just before Christmas and died just before 6 AM Friday at his Beverly Hills home, surrounded by his family.

Gavin starred as Julius Caesar in “Spartacus” and Steve Archer in “Imitation of Life.” He also won a Golden Globe for “A Time to Love and a Time to Die” when he played Ernst Graber.

Gavin leaves behind his wife, Constance Towers, 4 kids and 3 grandchildren.