Denise Michelle Crosby is an American actress and model known for portraying Security Chief Tasha Yar mainly in season one of Star Trek: The Next Generation, and Yar's daughter, the half-Romulan Commander Sela, in subsequent seasons. She is also known for her numerous film and television roles, and for starring in and producing the film Trekkies.

Natasha "Tasha" Yar is a fictional character that 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.