WordNet (r) 3.0 (2006):

leading lady
    n 1: actress who plays the leading female role

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "leading lady":
   actor, antagonist, antihero, bit, bit part, cast, character, cue,
   danseur noble, diva, fat part, feature attraction, feeder,
   first tragedian, headliner, heavy, heavy lead, hero, heroine,
   ingenue, jeune premier, lead, lead role, leading man,
   leading woman, lines, part, person, personage, piece,
   prima ballerina, prima donna, principal, protagonist, role, side,
   singer, soubrette, star, straight part, superstar,
   supporting character, supporting role, title role, villain,
   walk-on, walking part