Duvall, 67, who is almost unrecognizable in the promo for the interview, told McGraw that she knows she is ill.
“I’m very sick, I need help,” she said.
Duvall has been living in Blanco, Tex., since retiring from acting in 2002. In the interview with McGraw, which is set to air on Friday’s episode of “Dr. Phil,” Duvall described some of the symptoms of her illness — including her belief that former co-star Robin Williams isn’t dead but “shapeshifting.”
“The man who is threatening me is the Sheriff of Nottingham,” Duvall said in a clip from the interview.
Duvall’s acting credits include “Brewster McCloud,” “Nashville,” and “Popeye.