Curly Dadan is a close friend of Monkey D. Garp and the foster mother to both Portgas D. Ace and Luffy. After Ace's birth, Garp entrusted him to Dadan's care. Later on, he also left Luffy in her care.
Dadan resides on Mt. Corvo near Windmill Village, where she leads the mountain bandit group known as the Dadan Family. She is also a wanted criminal.
She was first mentioned following the Enies Lobby incident when Garp visited Water 7, claiming that he had left Luffy and Ace to train with a friend. Mayor Woop Slap later referenced her name after seeing Luffy's new bounty, asking, "Does Dadan know!?"
(Source: One Piece Wiki)
