Titania

Queen Titania was an Archfey of the Feywild, and the Queen of the Summer Court.

Background
Queen Titania used to set traps in the Feywild for outsiders. Once, a powerful balor named Naviask entered this plane to destroy it, and fell in one of those traps; Titania's magic changed the demon's essence and objective, turning him into a good fey spirit with the mission of healing scarred lands with nature.

Trivia

 * Outside Critical Role canon, Titania is considered both the queen of the Summer Court and the ruler of the Seelie fey. However, in Exandria she's solely mentioned as queen of the Summer Court, while Lady Elmenore the Unforgiving is the Archfey holding the title of "Matriarch of the Seelie Court", differentiating both courts.