Li'sar
From The Battle for Wesnoth Wiki
Acting the first half of the campaign as the antagonist, Princess Li'sar (b. 498 YW) unwillingly joins Konrad and Delfador as they fight together to defeat the trolls. As the two parties travel together in the Northlands, Li'sar begins to learn the truth of her authoritarian mother, Queen Asheviere.
She joins forces with Konrad in the final battle and overthrows her mother. She marries Konrad and becomes Wesnoth's newest Queen around 520-563 YW.
She is the main character (if chosen) in the game's tutorial.