She may be best known for her role as Robin Maxwell on the 1983 science fiction miniseries V, the 1984 sequel V: The Final Battle, and V: The Series. Other notable television roles include Chris Elliott's love interest, Charlene, on Get a Life.
Film roles include Fast Times at Ridgemont High (credited as Blair Ashleigh), Three for the Road with Charlie Sheen "A Sinful Life with Anita Morris, Inside Monkey Zetterland, Dream Lover with James Spader, and The Anniversary Party with Gwyneth Paltrow. Two of Tefkin's original songs appreared on The Anniversary Party soundtrack.
Blair was a member at The Groundlings where she also performed in the comedy "Just Like The Pom Pom Girls" (for which she won both L.A. Weekly and Dramalogue awards). She went on to star in the film version A Sinful Life as Baby Bump.
In 1996, Tefkin signed a songwriting and development deal with PolyGram Publishing and formed pop band Lucie Gamelon, singing and playing bass - Lucie Gamelon played the L.A. music scene for several years, as well as major dates on the 1998 Lilith Fair tour and released a six-song EP: Everything Is Nice.
Tefkin released her first solo CD Shocked & Devastated, on her own Bossyboots Records label in 2001. In 2004, Tefkin wrote and performed the critically acclaimed one-woman show In the Land of the Giants: A Tragicomedy With Music at the Blank Theatre in Hollywood.