Natalie Portman has been cast as the female lead in "Thor," Marvel Studios' adaptation of its comic book featuring the Norse god of thunder. Kenneth Branagh is directing.

Portman has been cast to star as Jane Foster, who in early comic book lore was a nurse who became Thor's first love. The studio said the character will be updated for the feature adaptation.

Chris Hemsworth is already cast as Thor. Tom Hiddleston is Loki, the god of mischief who serves as the movie's villain.

"Thor" is Marvel's stab at an epic fantasy adventure, spanning from present-day Earth to the realm of Asgard. The story centers on Thor, a powerful but arrogant warrior whose reckless actions reignite an ancient war. As punishment, Thor is cast down to Earth and forced to live among humans but once here, he learns what it takes to be a true hero when the most dangerous villain of his world sends the darkest forces of Asgard to invade Earth.

Marvel's Kevin Feige is producing.

Principal photography for the film is set for early 2010. The film will be released in the U.S. on May 20, 2011, distributed by Paramount Pictures.