Natasha "Tasha" Yar is a fictional character who mainly appeared in the first season of the American science fiction television series Star Trek: The Next Generation. Portrayed by Denise Crosby, Yar is chief of security aboard the Starfleet starship USS Enterprise-D and carries the rank of lieutenant. The character's concept was originally based upon the character of Vasquez from the film Aliens (1986). Following further development she became known first as Tanya, and then Tasha. Crosby had originally auditioned for the role of Deanna Troi, while Rosalind Chao became a favorite for Tasha. After Marina Sirtis auditioned for the role, the series' creator Gene Roddenberry decided to switch the roles for the actresses, with Sirtis becoming Troi and Crosby becoming Yar. Chao would later appear