Ebsen was originally cast as the "Tin Man" in the 1938 classic The Wizard of Oz. He recorded all his songs, went through all the rehearsals, and started filming with the rest of the cast. He was rushed to the hospital nine days after filming began, when his lungs seized after a week of inhaling aluminum dust from the dangerously experimental "tin" makeup. While Ebsen was in the hospital for two weeks, recovering from a near-fatal allergic reaction to the dust, he was silently replaced by Jack Haley. Haley didn't run the same risk because the makeup was changed in the meantime from a dust to a paste. Ebsen's career may have been damaged by losing the "Wizard of Oz" part; he appeared only in minor Westerns for many years after this incident.
Ebsen's work in television started as the sidekick to Fess Parker in the Davy Crockett series, but he became famous in 1962 when he starred as Jed Clampett in the television show The Beverly Hillbillies. The show depicted a stereotypical hillbilly family from the Ozarks getting rich on oil and moving to a stereotypical rich neighborhood in Beverly Hills.
Although scorned by critics, the show was a massive hit, attracting as many as 60 million viewers on CBS between 1962 and 1971. It was still earning good ratings when it was canceled by CBS because advertisers shunned a series that attracted a rural audience.
Ebsen also starred in the 1961 movie Breakfast at Tiffany's. He later starred in a TV drama series, Barnaby Jones, beginning in 1973. His last work was mainly in television, reprising his "Beverly Hillbillies" and "Barnaby Jones" roles.