While playing in "Guys and Dolls, he was asked to test for the role of an acerbic butler of a governor's mansion in "Soap," a primetime TV sitcom that satirized soap operas.
"The minute I saw the script, I knew I had a live one," he recalled in 2001. "Every role was written against type, especially Benson, who wasn't subservient to anyone. To me, Benson was the revenge for all those stereotyped guys who looked like Benson in the '40s and '50s (movies) and had to keep their mouths shut."
The character became so popular that ABC was persuaded to launch a spinoff, simply called "Benson," which lasted from 1979 to 1986. The series made Guillaume wealthy and famous, but he regretted that Benson's wit had to be toned down to make him more appealing as the lead star.