Patricia Beckmann was the original Six. The Terry Farrel, and then Gina Gershon.
Patricia was an artist at FIlm Roman, and was chosen for the voice of Six because of her voice over the office intercom. She was also a winner of the Playboy Animation festival – her entry was Matilda. Her work can be seen here: http://www.bunsella.com
Patricia has also done a series for the romp.com – Won & Twoo
She moved to NYC after the taping, and was unable to continue doing the voice. She is responsible for a lot of the character development for Six.