Lee Mendelson, the San Francisco-born producer credited with everything from scores of Charlie Brown TV specials to retrospectives on the 1915 World’s Fair has died at the age of 86.

Mr. Mendelson, who had lung cancer, died on Christmas Day 2019 at his Hillsborough home. Fittingly, he was perhaps best known for producing “A Charlie Brown Christmas” and for writing the lyrics to the song “Christmas Time Is Here.”

The music became synonymous with the show, but Mr. Mendelson said he didn’t toil over the lines. “I just wrote, scribbled some words down on an envelope, ‘Christmas Time Is Here, Happiness and so forth,’ and never thought much about it,” he said in a 2010 interview with the Television Academy Foundation.

Mr. Mendelson was raised in San Mateo and graduated from Stanford University in 1954. After three years in the Air Force and a stint working for his father, who grew and shipped vegetables, he started at KPIX-TV in 1961 writing public service announcements. His first production was a documentary on the 1915 Panama Pacific International Exposition in San Francisco. Made possible by discovery of old film footage, “The Innocent Fair” became part of a series that earned Mr. Mendelson a George Foster Peabody Award.

It was the beginning of a prolific career. Under his own company in 1963, he produced a documentary on the baseball star Willie Mays. Called “A Man Named Mays,” the made-for-TV project persuaded “Peanuts” creator Charles M. Schulz to accept Mr. Mendelson’s proposal for television programs based on “Peanuts” characters. “Well, if Willie Mays can trust you with his life, maybe I can trust you with mine,” Mr. Schulz said, according to the New York Times.

Thus, after chronicling the perhaps greatest living baseball player and inspired by a “Peanuts” comic strip depicting Charlie Brown’s foibles on the baseball field, Mr. Mendelson brought the world’s worst baseball player to the small screen.

Mr. Mendelson won 12 Emmy’s for his role in “A Charlie Brown Christmas,” the San Francisco Chronicle said. He produced more than 300 specials, among them more than 50 “Peanuts” television shows.

Other production credits included “Garfield on the Town,” “The Romance of Betty Boop,” “Travels with Flip (Wilson),” “From Yellowstone to Tomorrow,” “Children’s Letters to God,” and “The Unexplained” — a 1970 documentary narrated by Rod Serling about little understood scientific phenomena.

In 2015, Mr. Mendelson was entered into the Gold Circle, an honor society of the San Francisco Chapter of the National Academy of Television Arts and Sciences. The Gold Circle honors individuals “who have made a significant contribution to Northern California television” for 50 or more years. Other members include newscaster Belva Davis, television innovator James Gabbert, fitness guru Jack LaLanne, and television sports producer Franklin Mieul.

The NATAS profile of Mr. Mendelson includes a short video clip describing his career.