Effra

Effra was the daughter of Sybilla and the sister of Keel. She seemed to have some degree of control over her brother when he was transformed into a werewolf. She practised magic and at one point ordered Will to provide her with some of Don's hair after he rebuffed her advances, obviously with the intention of using it for magical purposes. Her mother reveals to Dr. Smith that Effra revels in the carnage the space croppers' plants create, and advises him to “just close his eyes” if she levitates him above the feeding plants.