Which future Oscar winning actress played Wonder Woman's sister, Drusilla, on the U.S. TV series "Wonder Woman"?

The future Oscar winning actress who played Wonder Woman's sister, Drusilla, on the 1976 - 1979 U.S. TV series "Wonder Woman" was Debra Winger. Diana Prince (Lynda Carter) was seen with her Little Sister Drusilla ('Wonder Girl', Debra Winger) on several of the very first episodes and then other occasions as the series ran.

In this original ABC (pilot + season 1) and then CBS (seasons 2–3) TV series, Wonder Woman is seen as having the strength of Hercules, the wisdom of Athena, the speed of Mercury, and the beauty of Aphrodite. She is seen as a true hero and a 'Wonder Woman'. As a beautiful Amazon princess, Wonder Woman travels to America disguised as Diana Prince. She is the assistant to the handsome but trouble-prone Major Steve Trevor (Lyle Waggoner).

Using her golden belt, which imbues her with astonishing strength, her bullet-deflecting bracelets, a golden lasso that dispels dishonesty, and an invisible supersonic airplane, Wonder Woman here combats evil all around the world.