As Elly May, she seemed blissfully unaware of her status as a bumpkin blond bombshell. Typically she was clad in a snug flannel shirt and tight jeans cinched with a rope belt, and she seemed to prefer her critters to any beau.
Chosen from more than 500 other actresses, Douglas said she felt at ease playing the role because, like her character, she grew up a poor Southern tomboy. Her childhood in Pride, Louisiana, came in handy when she was asked during her audition to milk a goat.
"I had milked cows before," she recalled in a 2009 interview with The Associated Press. "I figured they were equipped the same, so I just went on over and did it."
The show was not only assailed by critics, but by the network boss who put it on the air: "I HATED it," Michael Dann confided much later. "After screening the pilot, I don't think I ever watched another segment."
The public, however, felt quite the opposite: It ran for nine seasons, often in the Top 10. In their own way, the Clampetts were a forerunner of the '60s counterculture.
It wasn't much of a stretch for Douglas to fit into the troupe, said Smith, the niece.
"She was always happy, and she really loved animals — just like her character on 'The Beverly Hillbillies.' She was a wonderful lady, a very good Christian lady."
Indeed, when Douglas gave her autograph, she included a biblical verse ("Trust in the Lord with all your heart..."), according to New Orleans TV station WAFB.
Douglas' career began with beauty pageants — she was Miss Baton Rouge and Miss New Orleans — followed by a trip to New York to pursue a career in entertainment.
"That was the first time I had ever been on an airplane," Douglas said.
While modeling didn't appeal to her — "I didn't want to be that skinny" — television did. Douglas was featured as the Letters Girl on "The Perry Como Show" in 1957 and as the Billboard Girl on "The Steve Allen Show" in 1959.
She landed a featured role in the 1959 film "Career," starring Dean Martin and Shirley MacLaine, and a bit part in the film musical "Li'l Abner." She also had a small role as Tony Randall's secretary in the 1961 romantic comedy "Lover Come Back" with Rock Hudson and Doris Day.
Douglas starred in one of the most memorable episodes of Rod Serling's "The Twilight Zone" — titled "Eye of the Beholder," it was the one in which her head is wrapped in bandages for most of the half-hour after plastic surgery aimed at fixing her "ugliness," which in fact was beauty in a universe of monsters. And she starred opposite Elvis Presley in the 1966 movie "Frankie and Johnny."
After "The Beverly Hillbillies," Douglas worked in real estate, recorded country and gospel music albums and wrote a book for children that drew on biblical themes.
In 2010 she sued CBS and toymaker Mattel over a Barbie doll that used Elly May's name and likeness. The suit was settled in 2011.
She said she never minded being typecast as her "Hillbillies" character.
"So many kinds of people relate to Elly May," Douglas said. "So many people love her, and that means a lot to me."
Douglas was married twice, to Roland John Bourgeois, Jr. until 1954, and then to The Beverly Hillbillies director Robert M. Leeds. They divorced in 1980 after nine years of marriage. Survivors include her son, Danny P. Bourgeois.