Captain Janeway - I loved the character (but hated the "artisan bread" bun hairstyle). They created an entire series around a female captain, taking a crew into one of the most perilous and impossible missions ever- and wove in some complex human and political themes. Classic trek.
Star Trek The Next Generation - Dr. Leah Brahms (Susan Gibney) in episodes Booby Trap and Galaxys Child. She also played Commander Erika Benteen in the Deep Space Nine episodes Homefront and Paradise Lost. She was among the frontrunners for Captain Janeway on Star Trek Voyager. The role went to Genevieve Bujold, who left after production started. She also auditioned for the roles of Deanna Troi, Tasha Yar, Seven of Nine and even the Borg Queen.