Bellemere was the adoptive mother of Nami and Nojiko, appearing in a flashback during the Arlong arc.
A former Marine, Bellemere found Nojiko and Nami amidst the ruins of a town after a significant battle. She chose to leave the Marines behind to raise the two girls as her own daughters, seeking to escape the death and destruction that came with Marine life.
When Arlong arrived on her island, Bellemere was the only one who managed to put up any effective resistance. However, she was caught off guard by the fishmen's strength. In exchange for the safety of Nojiko and Nami, she allowed Arlong to kill her.
(Source: One Piece Wiki)
