Image caption Anderson also created Crusader Rabbit which was broadcast in the 1950s

Rocky and Bullwinkle creator and animation artist Alexander Anderson Jr has died at the age of 90.

The pioneering cartoonist, who had been suffering from Alzheimer's, passed away at an assisted living facility in California.

The show spawned movie spin-offs including The Adventures of Rocky & Bullwinkle (2000) which starred Robert De Niro.

Before Rocky and Bullwinkle, Anderson worked on Mighty Mouse.

Anderson's wife Patricia told the Associated Press news agency that the inspiration for Bullwinkle came from a dream he had where he was playing poker with some friends and a moose.

The character's name came from a car dealership in Berkeley called Bullwinkel Motors, which Anderson had found funny at the time.

Anderson began his own company with college friend Jay Ward.

The duo worked out of a garage behind Anderson's family home in Berkeley where they created Crusader Rabbit and his friend Rags the Tiger along with Dudley Do-Right of the Mounties and Rocky and Bullwinkle.

Crusader Rabbit was among the first animated series produced for television and aired on NBC in the 1950s.