Who plays freaky (naked) Mrs. Kersh in 'It Chapter 2'? Meet 86-year-old Joan Gregson

PASADENA, California – The absolute creepiest moment in "It: Chapter Two" has nothing to do with a clown.

Enter blood-curdling Mrs. Kersh, whose insane performance at tea with Jessica Chastain's Beverly dominated the Stephen King sequel's first trailer in May. Her character goes from kindly to sweaty frozen-face menace after delivering the line "You know what they say about Derry: No one who dies here ever really dies."

This was followed by a naked scamper in the dark behind the unsuspecting Bev, before Mrs. Kersh reveals her true monstrous self.

Freak-out alert: Mrs. Kersh is even scarier in the full film (in theaters now), leading to many firsts for veteran actress Joan Gregson, now 86: Her first horror film, her first breakout performance and, yes, her first nude scene.

"That was one condition about doing the role: They asked me if I would do a nude scene," Gregson says. "I listened to my agent, I drew a deep breath and said yes. I wanted this role. And I did the first nude scene I have ever done. At 85."

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"I've never had to turn any down before," she adds with a laugh. "No one had ever asked me."

The radiant Gregson is all kind smiles (really!) about her newfound horror success, sipping tea in the historic and suitably creepy Octagon House in Pasadena.

The actress has a long movie resume, with parts ranging from the Chopard clerk who helps Adrien Brody's detective in "Hollywoodland" to a mermaid alongside Hume Cronyn in the 1999 TV movie "Sea People."

She has been acting for 58 years but never worked in horror, she says. "And it’s wonderful – a whole new genre has opened up for me."

Gregson wanted the Mrs. Kersh part so bad during auditions last year that she repeated the character's name in silent prayer. "I was trying to remind the man upstairs that this was one I wanted. It was a lot of wishing trying to make it come true," she says.

But director Andy Muschietti says it was an easy decision and no accident that Mrs. Kersh is earning her spot in horror lore.

"It was very clear that it was going to be Joan. There’s something in her eyes," he says. "And the moment you see her performing, you know this is a serious actor."

Not only could Gregson bring the convincing warmth, but she turned on the menace as Bev figures out Mrs. Kersh is the daughter of Bob Gray, whose evil clown Pennywise is an incarnation of the shapeshifting creature referred to as "It."

Muschietti whispered commands (Freeze! Smile! Laugh!) to Gregson during her close-ups. But her frozen face with the dead smile was so powerful, even the crew murmured. "I realized this was going to be something really special," Muschietti says.

The nude prance in the darkened kitchen behind Chastain's Bev was shot on a closed set with Muschietti asking Gregson (by intercom) to try different walks.

Gregson's newfound fame has brought true fandom already. Arriving for the movie's premiere in August, she was pleasantly shocked when the hotel bellhop asked to take a selfie with her. "That’s the first time I have been recognized," Gregson says.

Her family (two daughters and five grandchildren) are "thrilled to bits" with her success.

"My daughter texted me after the trailer, asking, 'Are you naked?' I said, 'You have good eyes.' And she was like, 'Is that a yes or a no?' " Gregson says.

One fan even recut her kitchen walk, adding silly music."It’s very funny," Gregson says. "Oh, my sainted grandmother, whatever would she think?

"Goodness knows," she adds in answer to her own question. "Maybe she’s laughing about it right now."

This article originally appeared on USA TODAY: It Chapter 2: Creepy, naked Mrs. Kersh is horror newbie Joan Gregson