Dermot Mulroney gets around, doing rom-coms (“My Best Friend’s Wedding”), drama (“August: Osage County”) and indies (“Living in Oblivion”). With “Insidious: Chapter 3,” he adds horror to his repertoire. In this prequel, Mulroney plays the dad of a teen (Stefania Scott) haunted by a demon, trying to get her back with the help of the franchise’s psychic, Elise (Lin Shaye).

You said that the previous movies terrified you. Are you difficult to frighten?

I was sure that I would have to invent how to be scared in this movie. I thought I would have to really act and work really hard. But when I got on the set, it was dark and quiet, and there was creepy music. And the director created an environment that caused me to feel actually really scared. So it was much easier than I thought.

Did you have any nightmares after filming?

I didn’t stay scared after I left work. But one of the first days on the set, I came to work and saw the man who plays the bad guy. He had very elaborate wardrobe and makeup. And in fact, the demon he played represents illness and death. But I didn’t expect to see him, so when I turned around and saw the man in the special effects makeup was just standing in the dark corner of the set and doing nothing, it was very frightening. And even as I tell you this, I get kind of goose bumps on my arm.

Do you watch horror movies?

I do watch them. I have a teenage son, so I have seen some of the movies recently — “Paranormal Activity,” “The Purge,” and “Evil Dead.” And I have to take my son there so he can get into the movie [Laughs]. I was excited to try one for myself because I have only been in a few other movies that might be considered horrors. I love “Stoker” very much by Chan-wook Park, but it’s more like a murder movie.

Was Clyde excited to know that you are starring in “Insidious”?

Yeah. You know, when I told him that I was about to work with Meryl Streep on “August: Osage County,” he was not very excited. When I told him I was doing “Insidious,” he freaked out. He couldn’t believe it. He instantly took out his cell phone and text all of his friends: “my father gonna be in ‘Insidious: Chapter 3.’” Horror fans are a very fun group of people.  

You are famous for “My Best Friend's Wedding.” Why does your character chose Cameron Diaz and not Julia Roberts?

I can’t say why. It’s a reason why this film became a classic, and why it’s stayed relevant all these years later. Some movies I’ve done get kind of old and dated but this one still plays the same way. And I think the reason why it’s so good is because the girl doesn’t get the guy. It drives people crazy. I think that is why this movie remains so popular.