Saoirse Ronan stars in "Hanna," currently in theaters.

"I love Steve Martin and that kind of silly nonsense comedy. I'm a huge Steve Martin fan and I think that's one of his best.

"And you know a movie's good when there are so many great quotable lines in it. I'm always quoting that movie, though I can't think of a line now because I'm on the spot! I just love that movie. Seriously, I can watch it over and over again and never get bored."

Katrina Bowden currently stars in the hit show "30 Rock" and will next be seen in the feature film, "The Last Film Festival."

Penn Badgley currently stars as Dan Humphrey in the hit TV show "Gossip Girl," and will next be seen on the big screen in the Sundance thriller "Margin Call."

"She was brilliant in 'Greenberg' too. That's another one of my favorite comedies of all time.

"I actually had a fitting with Greta yesterday at Chris Benz and while we were talking it just reminded me how great she is, so I think Greta's comedies are my favorites right now. They're kind of my obsession at the moment!"

Sophia Bush currently stars in "One Tree Hill" and will next be seen in the feature film "Chalet Girl" with Ed Westwick.

"Gene Wilder can make you laugh and break your heart in an instant. I think he's one of the few people ever who have been able to rival Charlie Chaplin in that regard. And 'Blazing Saddles' really is hilarious.

"Gene Wilder and Cleavon Little are a perfect comedy team. I've watched it so many times and it always makes me laugh. When a movie touches you like that time and time again, it becomes a true classic."

Evan Rachel Wood is currently starring in the HBO mini-series "Mildred Pierce" and will next be seen on the big screen in "The Ides of March" with George Clooney and Ryan Gosling.

"I love that the premise sounds serious -- about gangsters and casinos and corrupt police in the '20s-- but then it just totally turns everything on its head and ends up being this hilarious movie. Plus, seeing Richard and Eddie dressed up in those suits with those mustaches -- it's pretty much worth watching just for that!

"I could watch it a hundred times and I still laugh every time. To me, that's what makes a comedy really great."

Selita Ebanks is a Victoria's Secret Angel who recently tried her luck on "The Apprentice."

"And, more recently, I also like 'Old School.' That's a good one. I knew it was good about five minutes in, but then it just keeps getting better. I like it when Will Ferrell gets the tranquilizer dart in his neck. Oh my God, that is so funny. I rewound it so many times when I first saw that, I was literally crying I was laughing so hard."

Michael Fassbender currently stars in "Jane Eyre" and will next appear in "X-Men: First Class," which hits theaters June 3.

"I love the scene when he opens the door, screams and shuts the door again. It's just full of those great moments that have you laughing out loud... I can watch the movie again and again and again. It always makes me feel happy.

"It always comes on TV, so it's easy to find. It's one of the movies that comes on and you don't mean to actually watch it, but then you can't change the channel and then it's ninety minutes later and your sides hurt from laughing so much."

Reshma Shetty currently stars in "Royal Pains" and will be seen next in the film "Not for Nothing."

"I don't know what makes it so special exactly, but I think it's a mixture of things. For starters, it's hilarious. Second, it's one of those movies that you quote your whole life. And third, the characters! What a great group of characters that movie has.

"It's a movie you really remember and it's just such a classic."

Mia Wasikowska currently stars in "Jane Eyre," and recently co-starred in the Oscar-nominated drama "The Kids Are All Right."

"My favorite scene is when Paul Rudd is really annoyed, but he's trying to look cool still, but he's picking up trash so he can't really look that cool. I'm not doing the scene justice with my description, but it's amazing.

"The whole cast is hilarious. When you've got people like Janeane Garofalo and David Hyde Pierce and Molly Shannon and Paul Rudd, how can it not be funny? Even the title is great. Don't you just want to run out and see that movie the minute you say it?!

Melanie Lynskey has been starring in the hit show "Two and a Half Men," and can currently be seen in the comedy "Win Win."

"The whole concept of two poor guys who think they're spies but are actually decoys for a nuclear war is just sick and hilarious. A story like that takes someone like Chevy Chase to pull it off though. He really made it work. He's great in that movie.

"I also love 'History of the World: Part 1' with Mel Brooks. I can watch those movies over and over, and I have been watching them my whole life. When I watch them I just sit down with a snack -- I like to eat peanut butter straight out of the jar with a spoon. That's all I need to be happy."

Bryan Greenberg currently stars on the HBO series "How to Make It in America," and will next appear in "Friends with Benefits," which hits theaters in July.

"I'd never seen anything like 'Tootsie' before. It was sort of the first of its kind. It's so heartwarming and so funny as well and the setting in the soap world. There's something about the character that Dustin Hoffman brings that's so convincing and so hilarious and dark.

"It is both drama and comedy. Drama teachers will say it's the same mask or something pretentious like that but it is really true: from great drama comes great comedy."

Rose Byrne stars in "Insidious" in theaters now and has "Bridesmaids" and "X-Men: First Class" arriving in theaters in the next few months.

"I can't even tell you how many times I've watched it, and it still makes me laugh. And isn't that what a great comedy's all about? Making you laugh. It's as simple as that. I love that movie!"

Gabrielle Union has recently appeared on hit TV shows "Army Wives" and "FlashForward." She will next be seen in the feature film, "Miss Dial" with Robinne Lee.

Jack Nicholson is absolutely perfect in that. He's Melvin! He's perfect! And he and Helen Hunt together, they both nailed it. Not every movie finds that kind of energy. But this one does, and it's so fun to watch.

"I love the scene when Jack Nicholson puts the dog in the trash compactor. I just feel so bad for that dog, but I can't help but laugh!

"That comedy is seriously as good as it gets."

Emmy Rossum currently stars in the hit Showtime series "Shameless."

"It's just really funny. I mean: A) Who knew Henry Fonda was that funny first off? and B) Barbara Stanwyck is probably one of the most talented comedic actresses of that century and this is one of her funniest performances. And besides those two, there are a million other reasons.

"Henry is this guy coming back from Amazon on a ship and, of course Barbara, a con artist, just latches right to him. And there's the standard parts where they fall in love and then they fight, but it's just so fresh the way they deliver the story. Even today it's fresh! And it's from the '40s!

"It's just a great movie. There are a million reasons it's a great comedy. I couldn't possibly name them all."

John Slattery currently stars in the hit show "Mad Men" and was recently seen opposite Matt Damon in "The Adjustment Bureau."

"I love how serious Gene Wilder is in it — he's really that way in all his comedies — which is why I love Gene Wilder! But in 'Frankenstein' in particular, it's like life or death to him and that passion magnifies the humor. Dr. Frankenstein is a serious guy, so it's not every actor who could find the humor in that part. The fact that Wilder could get there, that's what makes the comedy as a whole shine for me.

"Sometimes one actor can carry a whole comedy. That's Gene Wilder in this one... It's always funny. That's a movie that will be funny forever."

Amy Ryan currently stars in the hit show "The Office" and can be seen in theaters in "Win Win."

"First and foremost, I just love the clothes! That era of fashion is so polished and sophisticated. Somehow it makes the comedy stand out that much more when everyone looks like they should be acting so sophisticated because of how they're dressed! But more importantly, it's a film that just has great humor. I mean, it's from the '30s and the humor still works today. The banter between the characters, the way they needle each other, we do it just the same way today! Some things never change!

"When a film can survive that many decades and still be funny, that's really something special. That's the mark of a truly great comedy. It's definitely one of my favorites.

Kelly Rutherford currently stars as the very sophisticated Lily van der Woodsen on the hit show "Gossip Girl."

"Alan Arkin and Peter Falk just make that movie, but Alan Arkin especially. Alan Arkin is very good. I mean, he plays a dentist! A dentist named Sheldon! Can you imagine anything funnier than that? Just the idea of it is funny. The way he and Peter Falk play off each other, it's just pure comedic genius. Their timing is, well, it's perfect.

"It's an old film now, but the humor holds up today. I watch it every now and then and it always makes me laugh — sometimes before the punchline — and that's something special."

Paul Giamatti can currently be seen in "Win Win." He will next be working alongside Robert Pattinson in "Cosmopolis."