No cause of death was reported.
Beaver star Jerry Mathers, now 64, posted to his Facebook page Saturday: "I was so sad to hear today of the passing of my dear friend and business associate Frank Bank, who played Lumpy on Leave it to Beaver. He was a character and always kept us laughing. My deepest condolences to Frank's family."
Born in Los Angeles, Bank first appeared on screen as the very young Will Rogers in the 1952 Warner Bros. biopic The Will Rogers Story, and then managed to deliver other TV roles at the same time he was appearing on Leave It to Beaver.
Once the gentle sitcom about childhood was canceled, Bank continued to make sporadic TV appearances, including those on The Hollywood Squares, Family Feud and the 1983 TV movie Still The Beaver (it spawned The New Leave It to Beaver series, which ran four years) – although, in 1972, he had entered an entirely different profession: as a stock-and-bond broker.
According to a 1998 PEOPLE profile, Bank learned to handicap horses and read The Wall Street Journal during breaks on the Beaver set, where he also taught himself "everything there was to know about tax-free bonds." Within three years of getting started, he said, he was earning $300,000 a year at an L.A.-based company.
Among his clients were Mathers and Barbara Billingsley, who played Leave It to Beaver's matriarch, June Cleaver. As she once told PEOPLE: "Frank is certainly brighter than Lumpy Rutherford, and a very good stockbroker."
But then, he was never like Lumpy, really. In his 1997 autobiography Call Me Lumpy, he claimed that, during the Beaver years, he lived a life of wine, women and song – with maybe little emphasis on wine and song.
"A thousand women," Bank told PEOPLE, though his costars, including Eddie Haskell's alter ego, actor Ken Osmond, found the claim hard to swallow. "I never pictured Frank as being Don Juan," said Osmond. "But I never went on a date with him."
Someone who did, however, ended up becoming his second wife, Rebecca Bank. (Earlier, Bank had married his high school sweetheart and had two daughters.)
Rebecca told PEOPLE of their first encounter in 1981, "We met at a party and fell in love." The two, who shared a passion for tournament poker, divorced their respective spouses and immediately married, the magazine reported in 1998.