Who played Frasier's boss Kate Costas?

Mercedes Ruehl played Frasier’s boss, KACL station manager Kate Costas.

Kate appears in five episodes of Frasier during 1995 and 1996. She and Frasier have a combative professional relationship, frequently ending up on opposite sides of programming decisions and union negotiations. Their rivalry becomes personal when they begin a brief affair, adding romantic complications to their workplace conflict.

Kate eventually leaves KACL after accepting a management position at a Chicago station. Her tenure comes before Kenny Daly becomes the station’s long-term manager, so she belongs to the show’s succession of bosses overseeing Frasier’s radio career.

Ruehl was already a prominent stage and screen performer when she joined the sitcom. She won the Academy Award for Best Supporting Actress for The Fisher King and had won a Tony Award for Lost in Yonkers. The other options are easy to confuse with Frasier’s guest stars and recurring performers, but none played Kate Costas: the role belongs specifically to Mercedes Ruehl.