Willard's career included more than 300 projects, and he was perhaps mostly known for his roles in Best in Show and A Mighty Wind.
Most recently, he'd played Phil Dunphy's father Frank in the hit comedy series Modern Family.
The comedian, a master of the mockumentary genre, died of natural causes.
"A four-time Emmy nominee radiated a unique charm that established him as one of our generation's most gifted comic actors," Willard's rep wrote in a tribute.
"A master of sketch comedy, Fred was most heralded for his quick wit and improvisational expertise, which he demonstrated in hundreds of appearances on stage, on the big screen, and on a wide range of television shows."
