Rachel Corrigan is a psychiatrist and regular character from Poltergeist: The Legacy, serving as one of the members of the Legacy group. In Season Three's "Metamorphosis," however, Rachel was the main villainess.
She was played by Helen Shaver.
In "Metamorphosis," Rachel is performing a session with Elliot Black, an unstable patient who later snaps and attacks Rachel with a dagger after hearing voices in his head. Rachel is stabbed in her right arm, but after the attack, she begins hearing the same voices that Elliot heard, and is shown clutching the same dagger almost amorously. She also starts exhibiting changes in her behavior, often snapping at the other members of the Legacy. Rachel rants about them to a fellow psychiatrist shortly after her attack, and she later has another vision: this time one of killing Derek with the dagger. Rachel visited her psychiatrist again after Elliot killed himself in front of Nick and Derek, and like her last session, she ranted about Derek and claimed that he's trying to control her and the rest of the Legacy. Rachel turned heel and killed her psychiatrist with a blow to the head, doing so after he argued against her rants, and using a paperweight as a weapon. After killing him, Rachel slowly walked towards the body; smiling evilly at her handiwork to cement her villainous turn.
Derek and Nick learn that the dagger that Rachel was stabbed with is cursed, carrying an infection that causes paranoid thoughts to those who are stabbed. Meanwhile, the evil Rachel returned to the Legacy House and later attacked Alex. She later takes out the dagger with intent to either infect or kill Alex, but when she hears Kristen, she decides to go after her. Rachel overhears Kristen on the phone with Nick (who was warning her about Rachel) and later tries to attack her. After Kristen escapes, Rachel searches for her, and fights her off before chasing her again. She closes in on Kristen with the dagger in her hand, but she is accosted by Derek and Nick, who knock the object out of her hands. The group later performs an ancient baptismal on Rachel, which cures her of the infection.