Largely male throughout Europe, this name--spelled with or without the c, is an energetic choice that has really taken off for girls here; it's been used for the daughters of Steven Spielberg, Jerry Seinfeld, and Vanessa Williams. The Barack Obamas use Sasha as the nickname for their younger daughter, whose proper name is Natasha. Sasha Alexander, on the TV show Rizzoli & Isles, was born Suzana.
Sasha is a simplified spelling that originated in Russia as a diminutive for Alexander. And to add another spelling into the mix, there's Sacha Baron Cohen.
Though the Sascha spelling has never ranked here, Sasha, now Number 451, was as high as 147 in 1988. In France Sasha is completely unisex--Number 135 for girls, 128 for boys.