Kaitlin Olson says some people assume she’s mean

Kaitlin Olson is known for going blue. For 11 seasons — with a twelfth en route, and a thirteenth and a fourteenth already commissioned — she’s played Sweet Dee, member of the appallingly self-centered quartet on “It’s Always Sunny in Philadelphia.” But that’s not Olson. In person she’s a warm mother of two (and married to “Philadelphia” creator/star Rob McElhenney). Knowing that, it’s only mildly shocking that she pops up in “Finding Dory,” the latest Pixar romp, voicing a near-sighted whale shark super duper stoked to be reunited with Ellen DeGeneres’ absentminded regal blue tang.

Actors who go edgy sometimes say they actively sought out children’s fare because they wanted their kids or nieces or nephews to actually be able to watch their work. Being a parent of two, was that your idea, too?
This is certainly the first thing my kids have been able to see that I’ve done. That was awesome. I would absolutely do more Pixar films, or more kids films, as long as they are funny and good. There’s certainly some kids films I would not be interested in doing. [Laughs]

As a fan of Pixar, what is it like being in the middle of that machine?
The great thing about doing voiceover for these guys is [director] Andrew Stanton is a really great director for actors. He can act really well. When you’re reading with him you really feel like you’re working with another actor. That’s uncommon. It gives you the freedom to relax into it. I’m so used to working with actors. I’m not used to standing up there by myself and saying lines over and over. He makes it feel like you’re really in a scene with someone.

You’ve played a lot of scuzzy, nasty characters. But here you get to play someone who’s really, really nice and sweet.
The character didn’t start off nice. These characters take so many different shapes before they land on something. So I started off as a bit of a nemesis to Dory. I got to do a lot of that in the beginning. But then it slowly changed. They realized Dory needed support, and they wanted this idea of family being what you make it, and if you don’t have a family you can create one yourself. So I needed to be on her side. So she got nicer and nicer. It was fun to play someone nice. I’m used to bitchy roles. It’s a real stretch to be nice. [Laughs]

You seem nice in person.
I’m kidding, I’m a nice person. I met someone the other day who said, “Wow, I was expecting you to be really mean!” Because Sweet Dee’s so mean. I was like, [does a mousy voice] “No, I’m nice!”

You play another mean character on the forthcoming show “The Mick.”
It’s a very different character than Sweet Dee. But she certainly is a little nastier.

“It’s Always Sunny in Philadelphia” is an ensemble show. How have you taken to playing the sole lead?
In theory it was intimidating, because if this doesn’t go well it all lands on me. But when we were shooting it I was having so much fun. It’s a role I feel really comfortable in. I wasn’t nervous at all. I was very confident that it was funny and it was turning out to be exactly what I had envisioned. Look, if it bombs wildly it will all be on me. [Laughs] As long as I’m happy with it, I’m OK if it doesn’t do well. I’m not embarrassed by it in any way. I’m really excited for it. Let’s hope it does well, then I’ll take all the credit.

Follow Matt Prigge on Twitter @mattprigge