Elisha Cuthbert has come a long way from staring down a cougar as Jack Bauer’s oft-imperiled daughter on “24.” After a stint as the slightly daffy Alex Kerkovich on the much-loved but tragically canceled “Happy Endings,” Cuthbert decided to stick with comedy, and found her way to “One Big Happy.” The show, produced by Ellen Degeneres, finds her playing Lizzy, a lesbian who decides to have a baby with her straight best friend Luke (Nick Zano) just as he meets and marries Prudence (Kelly Brook).

What made you decide to move on to this show from "Happy Endings"?

I think I took the longest time to get on something else. Everyone was so brilliant on that show that it was a weird thing where I didn’t know what to do after that. I was a little bit shell-shocked. 

But you knew you wanted to stick with comedy?

I just had so much fun on "Happy Endings" that I felt like this was the perfect transition for me, and to be in front of a live audience is mind-blowing.

A live studio audience must feel pretty different.

Frightening.

It’s scary to go out in front of the crowd?

I got used to the workload that would come with it. I love the schedule, but I will never get over the fear. I feel like the fear is never going to leave me. I don’t know how other sitcom actors like the “Friends” cast or “Seinfeld” — I don’t know they felt about it, maybe they didn’t care, but I would love to know. Because I am literally petrified until that first take and then everything goes away.

Are you worried they’ll stop laughing at the jokes once you’ve done them a few times?

I feel confident in the writing that it’s going to be funny. It’s more that I don’t mess it up to the point where I’m embarrassing anybody. But I put the homework in, I do my job, I work hard, so I’m always overly prepared. For some reason in my mind, I think I’m going to be a disaster. And then I’m not, I’m actually a strong person on set, and I’m like, how did this happen, and why am I so afraid all the time?

What kind of feedback does Ellen provide?

Great notes. She comes and warms up the audience, which is terrifying, because then we have to follow the funniest human being. The best note she ever gave me was that we’re really going to have to believe in this friendship between Luke and me, which, as far as Lizzy’s concerned, is the most important relationship that she has. And Ellen was like, we have to believe that, and if we don’t believe that in every scene, then we have nothing. So she had great notes.

How do you feel about embracing a new character?

She’s actually the closest to a character that I’ve personally been connected to. Because I’m a little bit particular about how I like things. Not uptight, but I have a plan and I’m meticulous about things, and I'm a bit dorky.

Have the writers started adding that dorky side in for the character?

I think it already has been. I think there was a certain type and then as they started to see that I was a bit like that, it evolved. I mean, on "Happy Endings," I didn’t know I was a complete dodo until Season 2.