Naoise

The name Naoise means Warrior. Its origin is in the legend of Deirdre of Sorrows. Naoise is a warrior in the court of King Conchobar, he and Deirdre fall in love and elope to Scotland even though the King had claimed Deirdre for his own. Eventually, Naoise and Deirdre are promised that they can return to Ulster without consequence but it's a lie. Naoise is murdered, the King marries Deirdre and she eventually commits suicide.
It can be used as a unisex name and is spelled different ways accordingly.