William "Tex" Henson, 78, the animator behind the wisecracking chipmunks Chip 'n Dale, the flying squirrel Rocky and the beloved, dimwitted moose Bullwinkle, died Dec. 2 at a hospital here.

He died of head injuries after being hit by a pickup truck in Terrell, Tex.

Mr. Henson, a native of Dallas, joined the Walt Disney animation studios in California in 1944. He was a cartoonist for such Disney films as "Song of the South," "Pecos Bill" and "Peter and the Wolf."

Mr. Henson's first claim to fame was when he joined forces with another Disney animator to campaign for the comic chipmunk duo of Chip 'n Dale to become regular characters in Disney animation. Chip 'n Dale first appeared in "Private Pluto" in 1943 and went on to star in 23 theatrical cartoons.

He left Disney and after a stint in New York, where he worked on such cartoons as "Casper the Friendly Ghost," went to Mexico to supervise a studio that turned out some of the more memorable animated characters on television.

He supervised a team of about 180 animators who brought such characters as Rocky, Bullwinkle and the spies Boris and Natasha to life. The studio also turned out other cartoons featuring Underdog, Tennessee Tuxedo and the Trix cereal cartoon rabbit.

"There wasn't much expected from those cartoons," Henson told the Fort Worth Star-Telegram in an interview about 10 years ago.

"We were hacking them out on the cheap, getting the job done," he said, adding that most of his employees did not speak English or understand the humor of their work.

"But we made them as funny-looking as we could under the circumstances, and I guess something clicked between the writing and the cartooning," he told the paper.

Mr. Henson later moved to the east Dallas suburb of Terrell. He taught animation in the Dallas school system and drew cartoons for a small newspaper in the area.