What is the name of the first Star Trek series to feature a female captain as lead?

The first Star Trek series to feature a female captain as its lead was Star Trek: Voyager. Captain Kathryn Janeway, played by Kate Mulgrew, commanded the USS Voyager and was the series' central protagonist.

Voyager premiered on January 16, 1995, as the fifth Star Trek television series and helped launch the UPN network. Its premise separated the ship from Federation space: a powerful alien array stranded Voyager in the Delta Quadrant, leaving Janeway and her crew to begin an estimated 75-year journey home.

Janeway's leadership was especially significant because earlier Star Trek series had generally centered on male commanding officers. Voyager made a woman’s authority, scientific expertise, and responsibility for an entire starship central to the story. The show ran for seven seasons and 172 episodes, ending in 2001.

Deep Space Nine had important female officers and captains in individual episodes, and Discovery later placed women such as Michael Burnham in leading command roles. Neither changes Voyager's distinction as the first series with a female commanding officer in the lead role.