Co-stars Fred Gwynn (Herman Munster) and Al Lewis (Grandpa) were both stage trained actors who were stunned that Yvonne - known as a beauty queen -- had comedic acting prowess.
Yvonne later said she based her performance of Lily on the acting of Zasu Pittsl,a silent screen star.
"I found I had the ability to do comedy.My timing was really inborn."
Although Yvonne's Lily Munster, aka the Countess of Shroudshire, was an undead vampire hundreds of years old, she was still a beautiful woman.
"The Munsters" aired in black-and-white for 70 episodes (1964-66), but was canceled when it had to compete with "Batman," which aired in color.
Yvonne continued to sustain her career by reinventing herself. She sang opera at the Hollywood Bowl; she recorded singing albums; she appeared in stage musicals when movie roles became scarce.
In 1971 Yvonne starred in the Broadway musical "Follies," singing "I'm Still Here," a has-been's defiant anthem to the ups and downs of her career. Yvonne claimed that songwriter Stephen Sondheim wrote the song for her, and it won the 1972 Tony for best original musical score.
Yvonne continued working in film, TV and on stage until her health declined. She died in 2007 at age 84.