Harmon, who began playing Bozo in 1952 and later acquired all rights to the character, died of natural causes, his publicist said in a news release.
During a career of more than 50 years, Harmon not only played Bozo but also licensed consumer products featuring the trademark character. More than 200 others portrayed Bozo, including Willard Scott, best known as the longtime weatherman on NBC's "Today" show.
Harmon was also a producer of television animation, including shows featuring Laurel and Hardy, Popeye and Mr. Magoo.
A graduate of the University of Southern California, Harmon once told an interviewer he created his own network of Bozo shows in local TV markets in the days before cable and satellite TV. Harmon once estimated that about 10,000 hours worth of Bozo shows were created by local, licensed TV productions and that more than 5,000 consumer products bore the clown's likeness.
Harmon's wife and longtime business partner, Susan Harmon, an executive at Larry Harmon Pictures in Hollywood, said he was "the most optimistic man I ever met."
"He always saw a bright side," she said. "He always had something good to say about everybody."
In addition to his wife, Harmon is survived by a son, Jeff Harmon; and daughters Lori Harmon, Marci Brett-Carabet, Ellen Kosberg and Leslie Brett.
Video of Victoria’s Secret models trying to 'twerk' hits Instagram
Megyn Kelly: Santa Claus and Jesus are both white men