In an early episode of "The Beverly Hillbillies", Mr. Drysdale is showing Jed the mansion that is now his new home and happens to mention that the house was built by actor John Barrymore. Was Barrymore the original owner of the house that was used in the TV series?

It would seem that there is no connection between Barrymore and reality

https://en.wikipedia.org/wiki/Chartwell_Mansion
"The house was designed by Sumner Spaulding in 1933 in the style of a French chateau. It was built for engineer and contractor Lynn Atkinson,[3] who commissioned the property for his wife. She found it "pretentious", so the couple never lived there.[4] The house, located on 10 acres, with gardens designed by Henri Samuel, later was owned by Arnold Kirkeby and then Jerry Perenchio." Subsequently sold to Lachlan Murdoch.

Additional Information...

John Barrymore lived at the Beverly Hills Estate named "Bella Vista". He bought it from director King Vidor (The original owner) in the late 1920's and lived there until his death in 1942.

Also known as the Bella Vista, the Spanish Colonial home was built by notable architect John Byers in 1926 for Golden Age director King Vidor, whose films include "Northwest Passage" (1940) and "Duel in the Sun" (1946). Barrymore-a stage and film star with credits like "Grand Hotel" (1932) and "Midnight" (1939), as well as the grandfather of actor Drew Barrymore-purchased the home in the late 1920s and lived there until his death in 1942.

https://www.mansionglobal.com/articles/historic-barrymore-estate-in-los-angeles-sells-for-14-7-million-after-six-years-on-the-market-01631829468