Who was the first female Robot Master in the classic Mega Man series?

Splash Woman was the first female Robot Master in the classic Mega Man series. She appears in Mega Man 9, where she serves as one of the game's eight stage bosses.

Splash Woman was designed as a mermaid-like robot built to rescue people from sinking ships. After defeating her, Mega Man obtains the Laser Trident, a weapon that fires a piercing trident-shaped laser. Her underwater identity and rescue-oriented original purpose distinguish her from many Robot Masters designed primarily for combat or industrial work.

Roll is a frequent source of confusion. She is female and belongs to the classic Mega Man cast, but she is generally classified as a support robot rather than a Robot Master. Splash Woman therefore holds the usual canonical distinction for the first female Robot Master. Mega Man 9 was released in 2008, making her debut more than two decades after the original series began in 1987.