Stephen Fry — The fourth most popular account on Twitter (after Barack Obama, CNN and Twitter itself). Stephen Fry is a British actor, comedian, national treasure, etc. He’s done a lot of work with Hugh Laurie, including the classic “Jeeves and Wooster.” Sample tweet: “In the meantime I’m childishly amused by waiter who’s just told me about promotion: in his accent ‘two vodkas and you get a turd free’.”

Jimmy Fallon — After years on Saturday Night Live, Jimmy Fallon recently took over for Conan O’Brien on NBC’s Late Night. Sample tweet: “Watching Conan’s last late night. Really funny. Really nice. I really enjoyed him on late night. He’s gonna be great on the Tonight Show.”

Leo LaPorte — In many ways, king of the geeks. He spent years on Tech TV and now runs a podcasting network called This Week in Tech (TWiT – not related to Twitter). Sample tweet: “I have to say I’ve never understood Olberman’s appeal. And I’m a flaming liberal. I can only imagine what conservatives think.”

John Cleese — British actor and comedian who’s been in everything from Monty Python to Harry Potter. Sample tweet: “There’s an interesting 50%-50% split here – people who think pet hates = animals, and those who know it means what you love to hate.”

Levar Burton. How can you not love Levar Burton? He’s hosted Reading Rainbow for like 25 years, and was Geordi — the banana-clipped engineer — on Star Trek: The Next Generation. Sample tweet: “WTF? My rating on IMDB has jumped by over 700% this week. Must’ve been the guy wearing the Reading Rainbow tee-shirt on The Price Is Right!”

John C. Dvorak — Another Tech TV alum, John C. Dvorak seems to relish his cranky reputation. He is a regular panelist on TWiT, and also appears on Cranky Geeks, No Agenda and Tech 5. He writes for Marketwatch, too. Sample tweet: “WOZ on dancing with the stars!! WHAT?!?!?”

Michael Ian Black — A comedian who instigated a “Twitter War” with LeVar Burton. He’s best known for doing VH1’s I Love The… series. Sample tweet: “If you thought Vermont maple syrup would be less expensive in Vermont than at Trader Joe’s, you were wrong. God, were you wrong.”

Jeff Cannata. An actor, Jeff Cannata is best known as one of the hosts of the video podcast Totally Rad Show, where he and two other guys review movies, games, TV and more. Sample tweet: “Just watched Man on Wire – so glad it won the oscar! Such a beautiful expression of the power of art.”

There are plenty of other celebrities and semi-celebrities on Twitter – these are just the ones I follow. The awesome Mike Rowe also recently started tweeting, but hasn’t used his account much, so I didn’t highlight it with the others. But if you like Dirty Jobs, check him out.