The horror flick Oculus tells the story of a beautiful antique mirror whose most recent owners, siblings Kaylie (Karen Gillan) and Tim (Brenton Thwaites), are struggling to rebuild their relationship after the gruesome demise of their parents, 10 years earlier, While the two attempt to uncover the truth, they also begin to turn on each other, as the malevolent supernatural force of the mirror infects their minds and reflects their own insecurities.

At the film’s press day, Collider spoke to actress Karen Gillan for this exclusive interview about what attracted her to Oculus, being impressed with the short film version, why this character was a stretch for her, shooting a 13-minute monologue, and how much fun she had doing one of the film’s classic horror moments. She also talked about what made her want to sign on to play the female villain, Nebula, in Marvel’s Guardians of the Galaxy, that she’s only gotten to see the trailer so far, and how she won’t have to shave her head again, if they do any reshoots, as well as her decision to sign on for the ABC comedy series Selfie. Check out our Karen Gillan interview after the jump.

Collider: How did this come about? Once you finished Doctor Who, were you open to the possibilities, or were there specific types of projects you were looking to do?

KAREN GILLAN: I was pretty open. All I look for is good quality stuff. Whatever I read, if I like it, then I want to do it. It’s as simple as that. I don’t have a master plan of, “I should do this genre, and then this.”

Was there anything specific in this that particularly struck you with the story or character?

GILLAN: Yeah, I fell in love with the character. I think that she’s really, really interesting. She’s so damaged, for good reason, and that’s always interesting to play, as an actress. And I thought the script was so well-written. The time devoted to character development was really rare. And then, I watched the short film of Oculus that the director, Mike Flanagan made, and I was so impressed with that. I was like, “I have to do this!”

Did that short film really help you make your decision?

GILLAN: Oh, yeah! I watched that, and then I was like, “Okay, I’ll do it!” With anything, you can have a great script, but the execution is not there. But when I watched the short, I was convinced that the execution would be there.

Is this a character that you were able to identify with?

GILLAN: I don’t, a lot. That was actually a stretch for me. I had a really stable, normal upbringing. But, I think I can relate to really wanting something and really dedicating yourself to getting it. That’s what she’s doing with this mirror. So, I imagined that, and then tried to imagine the most extreme version. She just has tunnel vision.

Do you feel like it worked to your advantage to get to watch the younger actors doing their performance before you had to do yours?

GILLAN: Oh, yeah, sure! I went down to set and just watched what [Annalise Basso] was doing with the character, and she pointed out some really interesting things about the character. What Annalise came up with, that I thought was so clever, was that for the first half of the film, she’s protecting her brother emotionally, and then for the second half, she’s protecting him physically. I thought that was something I could definitely carry through into my version of the character.

Did watching her change your performance or how you wanted to approach it, or were you waiting to see her performance before you gauged your own?

GILLAN: I’d done loads of work on it, in terms of notes and just thinking about the character and writing stuff down. But, I was really open to whatever she did with it.

So much of this film is just you and Brenton Thwaites. Was it nice to have someone to go through all of this?

GILLAN: Yeah, totally! It was really fun, actually. We made each other laugh. There were scenes that we couldn’t get through because we were laughing so much, which is so weird because when you watch it, it’s so dark and scary. But, we had the best time. A lot of the film, for us in the present day, was just us two talking in a room. We barely ventured out of the room. So, all of our stuff was shot for the last four days of the shoot, which was quite an interesting experience.

How was it to shoot that 13-minute monologue?

GILLAN: It was something I’ve never done. It was like getting ready for a play. Mike Flanagan said, “I need you to be able to get through the entire thing in one take.” Not that he was going to use it in a one shot, but he needed me to do the whole thing, and then he’d cut to different angles. And not only did I have to do the whole thing, I had to do it all day, for 10 hours. By the end of it, I was fried. But also, I loved it. It was so extreme. There wasn’t an emotional logic to it. It was dates and facts, which is harder to remember. It didn’t really mean anything to me, emotionally.

The scene with the apple and the lightbulb is a classic horror movie moment. What was it like to shoot that, and then what did you think of the finished product?

GILLAN: That was really fun. I didn’t realize it was going to be so prominent, but we were shooting it and everyone was like, “This looks really good. Trailer!” It was just really fun to shoot, with the fake blood in the mouth and the sugar glass.

Was there a scene or a sequence that was most challenging to shoot?

GILLAN: Probably that monologue, to be honest, because I’ve never done anything like that before. I was talking directly to the camera. Other than that, there were things that we had to go to an emotional place for, but it was great.

In the past, the big superhero movies have been much more focused on the male characters than the female characters, but the Marvel movies are really focused on developing strong women. Was that part of the appeal of getting involved with the Marvel cinematic universe for Guardians of the Galaxy?

GILLAN: Oh, yeah! I don’t see the point in playing a character that doesn’t interest me, in anything. Also, this character is so cool. I didn’t get to read the script, though, before I signed on. I knew that she was the female villain and I was like, “Okay, that tells me that she’s going to be interesting.”

What did you have to audition with? Did they just give you fake sides?

GILLAN: I was reading a different version of a scene from the film, but that scene is not in the film. It was the same names and kind of alluded to the same thing, but the dialogue was all totally different.

Have you gotten to see any of it yet?

GILLAN: No, I’ve just seen the trailer like everybody else. I’m dying to see it!

Do you know yet, if you’ll have to do any reshoots or additional footage?

GILLAN: I think they always do reshoots, as a rule. They’re booked in before you even shoot the film, so probably. But, I don’t know yet.

Would you have to shave your head again?

GILLAN: Oh, no. I think they’d work around it because there’s such a small amount of hair.

Was it just very liberating to shave your head, or did you have any moments of tears while they were doing it?

GILLAN: No, I was laughing hysterically. It really hit me when I woke up the next morning. That’s when I was like, “Oh, my god, where’s my hair?!” But also, everyone kept me in good spirit. Everyone was laughing and telling jokes. Marvel are the best company to work for, they really are. They treat you really well. They made my hair into the most incredible well-made wig and they gave it to the Star Wars people. It’s just so funny to think that my hair is made into a wig, next to all these Star Wars monster heads in a warehouse. I thought that was really funny.

Did you have to sign a multi-picture deal, and was that something you were nervous about?

GILLAN: I can’t really talk about that because I feel like that’s going to give away the ending of the character. But I’d be open to it, if they’d want me to.

Did you have any funny interactions with kids or people that saw you in full character with the make-up?

GILLAN: Yeah, there were a few people that came down to set, but generally, they make you wear a secrecy cloak when you’re outside. When they talked to me, people would [look at me funny]. That became normal.

What attracted you to the ABC comedy series Selfie?

GILLAN: It was so much fun! I wasn’t actively looking [to do something like that], but when it came along, I couldn’t refuse. It was one of those. I just love the character so much. She’s really American.

Oculus opens in theaters on April 11th.