Matt Damon
The Jason Bourne star isn't sure if he'll ever join the Twitterverse. "Twitter seems like a great way to keep in touch," he told Buzzfeed. "I just never believe that my first response to anything is the one I want to go on record with, you know. I'd rather reflect a little bit."
Jennifer Lawrence
"I will never get Twitter," Jennifer tells BBC Radio 1. "I'm not very good on [a] phone or technology...the idea of Twitter is so unthinkable to me."
Jennifer Aniston
"If I took to Twitter or anything, I would really send people over the edge," the actress told ABC News, "probably just correcting every false rumor."
Mary-Kate Olsen & Ashley Olsen
"We've spent our whole lives trying not to let people have that accessibility, so [joining Twitter] would go against everything we've done in our lives to not be in the public," Mary-Kate told Vogue.
Tina Fey
Unbreakable Kimmy Schmidt's Titus Burgess tried—and failed—to get his boss to join Twitter. As he explained on Late Night, Fey asked, "Why would I give my jokes away for free?"
George Clooney
"If you're gonna ask people to pay money to come see you in a movie, they don't need to know your every thought all the time," George told Fusion. "I think there has to be some element of mystery. There's a real danger when you're really famous...I could say something, go to sleep, and wake up in the morning and my career be over."
Julia Roberts
Twitter is "like screaming into the wind," Julia once told E! News. "I guess I just don't get it."
Dakota Fanning
"I don't really need to let people know where I am and what I'm doing," Dakota told Wonderland. "I don't have a Facebook or Twitter, and I won't ever."
Mila Kunis
"It frightens me. It does," the actress said on The Late Late Show. "I just don't think people need to know when I'm going to the restroom. What am I gonna tweet? Like, 'Hey, now I'm moving from room to room.' I don't really know what I would tweet people."
Daniel Radcliffe
Though Radcliffe has a Google+ account, he told SkyNews, "I don't have Twitter and I don't have Facebook, and I think that makes things a lot easier because if you go on Twitter and tell everybody what you're doing moment to moment and then claim you want a private life, then no one is going to take that request seriously."
Emma Stone
"It's that need to be liked, that need to be seen, that need to be validated, in a way, through no one that you know. And so people ask the question about fame, or what it feels like, and it seems like everybody knows what that feels like. It seems like everyone's cultivating their lives on Instagram or on different forms of social media, and what pictures looks best of their day," Stone told The Los Angeles Times of being Twitter-free. "It's this very modern 'keeping up with the Joneses.' It's almost impossible to find someone that's not, in some way, on the Internet."
Angelina Jolie
Like some other celebs, Jolie has taken ownership of @angelinajolie. However, the account is locked and she has never tweeted.
Kristen Stewart
The actress is definitely not a fan of social media. "Twitter f--ks me over every day of my life," Stewart told Flaunt. "Buy a camera and you're paparazzi; get a Twitter account and you're an informant. It's so annoying." She also ranted to USA Today, "What would I tweet about? Who are you talking to? what are you saying? I can't even understand it."
Daniel Craig
"I am bloody not [on Facebook]. And I'm not on Twitter either," the actor told BBC America. "'Woke up this morning, had an egg.' What relevance is that to anyone?"
Sandra Bullock
"I don't want anyone to know where I am," the private star told Vogue.
Scarlett Johansson
"I'm always surprised that certain actors have Twitter accounts. I guess they use it in a way that works for them," the actress told Interview. "But I'd rather that people had less access to my personal life. If I could keep it that way, I'd be a happy lady."
Jake Gyllenhaal
The actor has not joined Twitter, although it appears he has claimed the username @jakegyllenhaal so nobody can impersonate him.