Kim-CattrallKim Cattrall is best known as the smart, sassy — not to mention hot — Samantha Jones in the “Sex and the City” HBO series and now movies. But she gives a remarkably credible performance as Samantha’s antithesis, a washed-up prostitute and porn star.

Cattrall stars in the indie movie “Meet Monica Velour,” that recently premiered at Tribeca Film Festival.

While both her characters share a certain sexual appetite, they occupy opposite ends of the scale.

Samantha is an independent well-to-do executive, while Monica, is a down-on-her-luck woman who is saddled at middle-age with a bad reputation, a bad relationship and a disillusioned daughter.

Kim talked to New York magazine about the role, for which director Keith Bearden wanted her to pack on the pounds.

“He was very adamant about me gaining a lot of weight. He wanted me to gain like 35 pounds! Really, just for health reasons I couldn’t do that,” she said.

“I also didn’t have enough time to do it safely with a doctor’s care. But what I did was I put on fifteen pounds, and that was comfortable. I could do that. I just didn’t exercise at all.”

Cattrall also talked about her two characters, what they shared, and how they are different.

“There are a lot of things that make up a woman, a person. I have days when I’m very lonely and depressed. I mean, this is a story about a woman who’s in dire straits, really, and can’t find a way out.

“Our stakes are not that high. We’re not just surviving. We’re prospering. We live in the world. She lives outside of the world. She’s like a castaway. You look at someone like [late adult-film star] Marilyn Chambers — what happened to these people?”

“There were days when I didn’t even have any makeup on. There were days when they actually changed the light to make me look harder and more overweight or just more fucked up,” she says about playing a character who is down on her luck.

“I didn’t see the dailies on it because I thought, You know, I’ve made a stand here that I’m gonna do this in a very truthful way, and if I look at them they might scare me.”