Knotts -- best known for playing deputy Barney Fife in the 1960s and Ralph Furley in the 1970s -- died at Cedars Sinai Medical Center Friday, the Los Angeles Times said Saturday.
His longtime friend and co-star, Andy Griffith, was one of the last people to see him Friday night. Knotts won five Emmys for his work on "The Andy Griffith Show."
Knotts most recently voiced the part of Turkey Major in Walt Disney's "Chicken Little." He appeared as a guest on NBC's "Las Vegas" and Fox TV's "That '70s Show" last year.
His many film credits include "The Apple Dumpling Gang," "Pleasantville," "Cat's Don't Dance," "The Incredible Mr. Limpet," "The Ghost and Mr. Chicken" and "The Reluctant Astronaut."
Knotts told the Times in a 1976 interview that he turned to comedy as a way to help ease the memories of an unhappy childhood.
"I felt like a loser," he said. "I was unhappy, I think, most of the time. We were terribly poor and I hated my size."
He was born Jesse Donald Knotts in Morgantown, W.Va., on July 21, 1924, the youngest of four brothers.