Helen Rachel Slater (born December 15, 1963) is an American actress and singer-songwriter. She is best known for playing the DC Comics superheroine Supergirl in the 1984 film Supergirl, as well as appearing in films such as The Legend of Billie Jean (1985), Ruthless People (1986), The Secret of My Success (1987), City Slickers (1991), Chantilly Lace (1993), and Lassie (1994). She provided the voice of Talia al Ghul in Batman: The Animated Series, portrayed Lara-El in Smallville, and played Eliza Danvers in the 2015 Supergirl TV series.
Source : Wikipedia