McCormick died Friday at the Motion Picture & Television Hospital in Woodland Hills, Calif., where he had been since a stroke in 1998, the Los Angeles Times reported Saturday.
His longtime friend and fellow comic Shelley Berman told the Times Friday: "Few, very few, will ever be able to craft a joke as beautifully as Pat."
McCormick wrote the classic Carson one-liner: "Due to today's earthquake, the God is Dead rally has been canceled."
The Ohio native originally wanted to be a lawyer. After graduating from Harvard, he dropped out of Harvard Law School, did a short stint in advertising and started writing material for Jonathan Winters, Henny Youngman and Phyllis Diller.
He wrote for Jack Paar, Merv Griffin, Red Skelton and Danny Kaye. He appeared on and wrote for "Candid Camera." He was a regular on "The New Bill Cosby Show" and a fixture at the legendary Friars Club roasts.
McCormick is survived by his son, Ben McCormick, and a grandson.