Betsy is most known by her role as the main female lead, Penny Lace, in the Vinewood clasic film, Bullwhip Fury. Betsy was considered "America's sweetheart" in 1952, despite accusations that she engaged in sexual relationships with movie directors and producers to get some of her roles. She has been referred to by some people as "the Poppy Mitchell of her time".
O'Neil was one of the actresses considered for the female lead in the 1975 film The Many Wifes of Alfredo Smith but at 40 was considered too old for the role. Leonora Johnson, a much younger actress, was also considered for the role before she was murdered. This led to suspicion that O'Neil had murdered Johnson as an act of revenge, until it was later revealed she was murdered by director Peter Dreyfuss.
Betsy O’Neil is most likely based on the former first lady, Nancy Reagan. They were both actresses back in Hollywood's Golden Age. She is Dutch London's second wife, who is supposed to share parallels with the former actor and U.S President, Ronald Reagan. Betsy O’Neil co-starred with Dutch London in Bullwhip Fury, just like Nancy co-starred with Ronald Reagan in Wagon Train and The Tall Man.