Frank Bank, who as Clarence “Lumpy” Rutherford served as the dimwitted foil to “Beaver” Cleaver and brother Wally on the classic TV comedy “Leave It to Beaver,” died April 13. He was 71.

A spokesman for Hillside Memorial Park in Los Angeles confirmed Mr. Bank’s death but did not disclose where he died or the cause.

Mr. Bank had a number of illnesses and was hospitalized recently in Rancho Mirage, Calif., said Jerry Mathers, who played Beaver Cleaver in the popular series, which ran from 1957 to 1963.

“Leave It to Beaver” revolved around young Beaver and his misadventures, which usually involved the teenage Wally and Wally’s friends — skinny, sarcastic Eddie Haskell and oafish, overweight Lumpy, who loved pushing Beaver around.

“Lumpy was the ultimate bully, but Frank was a very, very kind and gentle person and a very good actor to play it so well,” Mathers told the Los Angeles Times this week. “The show was about all the people you knew growing up and throughout your life, and Frank brought that perspective to the show.”

After the show ended, Mr. Bank was chosen to play comic book character Archie Andrews in the pilot for a new series but found he could not shake his previous TV identity. “That’s not Archie, that’s Lumpy,” Mr. Bank, in a 1998 People magazine interview, recalled hearing the sponsor say.

Discouraged by the typecasting — and not wanting “to be like George Reeves, who could only be Superman,” he said — he decided to give up on acting to pursue business.

While others read Daily Variety, Mr. Bank said he read the Wall Street Journal during breaks on the “Leave It to Beaver” set. Later, he helped his parents at the meat market they owned and taught himself about stocks and bonds.

By the mid-1970s, he was earning a six-figure income as a stock-and-bond broker in Los Angeles. Among his clients were former co-stars Mathers and Barbara Billingsley, who had played Mrs. Cleaver. “Frank is certainly brighter than Lumpy Rutherford, and a very good stockbroker,” Billingsley said in the People magazine article.

Born in Los Angeles on April 12, 1942, Mr. Bank made his acting debut in 1950 with an uncredited appearance in the movie “Cargo to Capetown.” He had small parts on television before joining the cast of “Leave It to Beaver” and becoming forever linked to the Lumpy character.

He rarely brought up his role in the iconic sitcom until after he married and had children old enough to wonder what their father did when he was younger. Then, he told Orange Coast magazine in 1989, “they were so proud, I became proud.”

He reprised the Lumpy role in the 1983 TV movie “Still the Beaver” and the series “The New Leave It to Beaver,” seen on the Disney Channel and later WTBS from 1985 to 1989.

A longtime resident of the San Fernando Valley, he wrote a memoir, “Call Me Lumpy” (1997). Subtitled “My Leave It to Beaver Days and Other Wild Hollywood Life,” it drew attention mainly because of a bawdy chapter detailing his “perpetual sexfest” during the 1960s. “I have slept with over 1,000 women,” the chapter begins.

The introduction to the book was written by Ken Osmond, who played Eddie Haskell on “Leave It to Beaver” and later was a Los Angeles police officer until he was shot in the line of duty and retired.

Mr. Bank’s survivors include his wife, Rebecca; four daughters; and five grandchildren.

— Los Angeles Times