The Yaksha with whom Shikandini changed her sex.
Bhishma brought her back, but Salva now refuses. Vichitravirya is also not ready to marry her. So she asks Bhishma to marry her. However, he sticks to his vow not to have a wife.
Amba swears vengeance on Bhishma. She takes her own life and is born again as Shikandini, daughter of King Drupada. Changes her sex with the yaksha Sthuna and becomes the man Shikandin.
Shikandin is the reason Arjuna was able to incapacitate Bhishma in the Mahabharata War.