The Australian star, known as the boy from Wagga Wagga, became one of Tony Hancock's radio sidekicks in the 1950s.
He moved to the UK in 1947 and went on to star in the The Dam Busters, Doctor Who and The New Adventures of Black Beauty. He also played Ben Bishop in the 1960s BBC soap opera Compact.
As a child star he began his career in "Huckleberry Finn life" in New South Wales and made his first film appearance in 1933's Harmony Row, in which he was billed as "Willie" Kerr.
He went on to be seen in TV mini-series Anzacs, horror film Razorback and the 2003 version of Peter Pan.
Kerr, known for his catchphrase "I'm only here for four minutes", appeared in the 1950s and 1960s alongside comedy greats Sid James, Spike Milligan, Kenneth Williams and Peter Sellers.
He starred in Spike Milligan and John Antrobus' 1962 play "The Bed-Sitting Room" as well as 1963 film The Wrong Arm of the Law with Peter Sellers and Bernard Cribbins.
He starred with Patrick Troughton, the second Doctor, in The Enemy of the World, playing the role of Giles Kent.
Returning to Australia in 1979, he had a role in 1981 film Gallipoli.
He died at his home in Perth while watching Seinfeld.
According to family members, Kerr was watching television.
"Mum said she could hear him laughing to Seinfeld," his son Wilton told ABC News.
"That was one of his favorite shows."