Helen Rachel Schlacter

It's not often an actress can play a character, then play the character's aunt 24 years later.
Helen was the first actress to play Supergirl / Kara Zor-El in any medium in Supergirl: the Movie (1984)!
In 2008, she played Kara's aunt, Lara-El (birth mother of Kal-El / Clark Kent), in two episodes of Smallville! (She also appears in a documentary on the Season 7 Smallville DVD set entitled "Supergirl: Last Daughter of Krypton")
And she still looks...well...SUPER!
Currently a regular on the new TeenNick series Gigantic as Jennifer Moore.

Over three dozen film and credits...
genre appearances include:
Supernatural"Family Remains"
Eleventh Hour"Medea"
Smallville(Lara-El)
Steal (Kim)
Nowhere in Sight(Carly Bauer)
Michael Hayes (Julie Siegel)
House in the Hills(Alex Weaver)
Supergirl
(Kara Zor-El aka Linda Lee Danvers aka Supergirl)
Dream On(Sarah)
Batman: the Animated Series(Talia al Ghul)
ABC AfterSchool Specials "Amy & the Angel"
12:01(Lisa Fredricks)
Check out...
Helen Slater's Official Page
Tribute to Helen Slater

Other actresses to play Supergirl / Kara Zor-El / Linda Lee Danvers since Helen include
Nicolle Tom (Superman: the Animated Series, New Batman Adventures, Justice League Unlimited)
Laura Vandervoort (Smallville)
Tara Strong (Justice League Heroes video game)

Other actresses to play Lara-El aka Lara Lor-Van before Helen include...
Agnes Moorehead (Adventures of Superman [radio] "The Baby from Krypton" [1940], "Superman Comes to Earth" [1942])
Luana Walters (Superman[1948 movie serial] "Chapter 1: Superman Comes to Earth")
Aline Towne (Adventures of Superman "Superman on Earth")
Susannah York (Superman the Movie, Superman II, Superman IV: the Quest for Peace)
Britt Ekland (Adventures of Superboy "Escape to Earth" and "Abandon Earth")
Eliza Roberts (Lois & Clark: the New Adventures of Superman "Foundling")
Finola Hughes (Superman: the Animated Series "The Last Son of Krypton")
and, Kendall Cross on an earlier episode of Smallville ("Memoria")

Other actresses to play Talia al Ghul include...
Olivia Hussey (Superman: the Animated Series and Batman Beyond)
Andrea Bowen (Batman: the Brave and the Bold)