In Avatar, which actress played the scientist Dr. Grace Augustine on Pandora?

In Avatar, Sigourney Weaver played the scientist Dr. Grace Augustine on Pandora.

Weaver’s character leads the Avatar Program and studies the biology and culture of Pandora. Dr. Augustine is an exobiologist who understands that the Na’vi and their environment cannot be treated merely as obstacles to mining. She supports scientific cooperation and opposes the military-backed destruction of the Na’vi’s home.

The role reunited Weaver with science-fiction cinema after her famous performances as Ellen Ripley in the Alien film series, although Grace Augustine is a different character with a different profession and story. Avatar used motion-capture performances for the Na’vi and several other digital characters, while Weaver performed as both the human scientist and, through the film’s fictional technology, a participant in the avatar program.