Marshall Efron, an actor and humorist who was a core figure in two of the quirkiest television shows of the 1970s, “The Great American Dream Machine” and the children’s program “Marshall Efron’s Illustrated, Simplified and Painless Sunday School,” died on Sept. 30 at the Lillian Booth Actors Home in Englewood, N.J. He was 81.

His longtime writing partner, Alfa-Betty Olsen , said the cause was cardiac arrest.

At a time when “Gunsmoke,” “Bonanza” and “Marcus Welby, M.D.” were among television’s top-rated shows, Mr. Efron made an idiosyncratic entry into the viewing public’s consciousness as a parody of a consumer affairs reporter on “The Great American Dream Machine,” a hodgepodge of a series that premiered in January 1971 on PBS, then newly formed and still known as the Public Broadcasting Service .

It was a freewheeling mix of short comic films, cartoons, musical acts, humorous sketches, investigative journalism and opinion pieces, and Mr. Efron, 5-foot-5 and weighing well north of 200 pounds, cut a distinctive figure on it. The New York Times once called him “the big man daintily wielding a satirical sledgehammer.” Another time, the newspaper described him as “the plump elf with the crab grass mustache.”

In one bit, Mr. Efron riffed on the United States Department of Agriculture’s grading of olives. “Which is the biggest — the giant, the jumbo or the extra large?” he asked.