Story highlights Character actor dies in his sleep at home in California

Cause of death unknown

Burkley known for voicing 'King of the Hill' characters

Dennis Burkley, the character actor known for his work on TV's "King of the Hill," has died, his agent tells CNN. He was 67.

Burkley's agent, David Ankrum, says the actor died in his sleep late Saturday or early Sunday, at his home in the Los Angeles suburb of Sherman Oaks. A cause of death has yet to be determined.

Ankrum praised his brawny friend of more than 40 years, saying "Dennis could do both comedy and drama, and he had a tender side -- he didn't look it, but he did."

Burkley's recent TV roles included a stint on "My Name is Earl," and giving voice to several characters, including Principal Moss, on "King of the Hill."

Ankrum says the actor's favorite roles included a mute motorcyclist in "Mask," one of Kevin Costner's buddies in "Tin Cup," and working with James Garner on "Murphy's Romance" and Redd Foxx on TV's "Sanford." Burkley had more more than 130 credits in movies and on TV.

Burkley had been in semi-retirement the past few years, focusing on voice work and producing small movies, according to Ankrum.

The actor is survived by his wife, Laura, a son, Shawn, and a daughter, Shannon.