Which supporting performer was called the unofficial 'Seventh Python'?

Carol Cleveland was the supporting performer commonly called the unofficial “Seventh Python.” Although she was not one of the six core male members who created and starred in the series, she appeared frequently and became an important part of the show's ensemble.

Cleveland supplied something the Pythons deliberately lacked in their main lineup: a regular female performer who could play characters beyond the troupe's often exaggerated use of men in drag. She appeared in numerous sketches as wives, girlfriends, glamorous figures, authority figures, and comic foils. Her performances helped broaden the show's character world while preserving its fast, absurd style.

The nickname was affectionate rather than an official membership title. The six principal Pythons were Graham Chapman, John Cleese, Terry Gilliam, Eric Idle, Terry Jones, and Michael Palin. Other recurring contributors, including musician Neil Innes and performers such as Connie Booth, were also significant to the Python world, which is why fans sometimes debate who deserves informal “additional Python” labels. Cleveland's repeated presence on the television series made her the clearest traditional answer.