How could you not? You expect the manic energy of Ace Ventura; the dim-bulb charm of Lloyd Christmas in "Dumb & Dumber''; even, sigh, the "Grinch.''
But that's merely our perception, as well as a sign of how indelibly Carrey has created those characters. Why don't we, instead, expect Joel from "Eternal Sunshine of the Spotless Mind''? Or even Andy Kaufman from "Man on the Moon''?
For whatever reason, audiences are more willing to buy Carrey in a broadly comic role than in a serious one.
So what, then, is a Jim Carrey role?
Let's ask the man himself.
"Oh gosh, I wouldn't even know,'' Carrey said recently during a phone call from a Los Angeles hotel. "To me, it's the characters, not me. I wouldn't know how to drill down or label myself in any way.''
Then we'll have to do it for him.
"To a majority of the public, [Carrey] was known primarily as a charmingly insane comedic force of nature,'' says F. Miguel Valenti, the director of film and media production at Arizona State University's School of Theatre and Film. "However, as he has proved time and again in his career, he is a gifted dramatic actor. . . . In fact, his most compelling performances have been of the more serious variety.''
Then how come we know him primarily as a nut-case comic, more Jerry Lewis than Laurence Olivier?
"It's amazing how fickle the perceptions can be,'' says Will Ferrell, who knows something about trying to break out of the comedy box from time to time.
And perceptions are hard to overcome. If you first got famous by talking out of your rear end, a dramatic character is probably going to be a tougher sell.
Carrey is, without question, a talented actor. Valenti, in fact, called him "one of those 'poor, unfortunate' people who are blessed with just too darn much talent'' - so successful in one realm that audiences have trouble accepting him in another.
"His list of credits has shown a vaulting from the comedic to the dramatic and back again with little perceived effort,'' he says.
Comedy is where he started and the place to which he occasionally returns.
His humor tends more toward the cartoonish, which is no doubt why he is the voice of Horton in the big-screen version of "Horton Hears a Who,'' which opens Friday in Utah.
And why he played the title character in 2000's "How the Grinch Stole Christmas,'' even though the roles are quite different.
"It's like alpha and omega Dr. Seuss,'' Carrey says, "going from the Grinch to this innocent character that just finds joy in everything and just wants to love the world and everything in it.''
With their broadly imaginative characters and stories, filmed versions of Seuss books would seem to be the perfect vehicle for Carrey. He's certainly a fan.
"Dr. Seuss is rock and roll,'' Carrey says. "He brings out that sensibility in people. . . . It will never go out of style. It was alternative then, and it will always be alternative. There's really something for everybody. Creatively, it's just so rich. There's a really sweet message disguised by a really out-there planet.''
For all that, Carrey's stint as the Grinch was largely panned. His tendency to go over the top works much better in a film like "Dumb & Dumber,'' which is gleefully stupid by design. But part of the backlash is messing around with childhood memories, as well. It's a danger Carrey faces again with "Horton'' - but one he can't really consider.
"You've got to damn the torpedoes,'' he says. "You've just got to jump in and say, 'There's something inside me that is this character.' ''
It's probably not surprising that Carrey is much more subdued - and less dramatic - in conversation than on film. He's only made a couple of movies in the last three years, so the natural question is: Where have you been?
"It's just cyclical,'' he says, laughing. "Sometimes you want to work a lot and sometimes you want to work a little. There are times in your life also when you want to take a look at your life and the people in your life and spend time with them, and not just be about the business."
People in his life include actress and former Playboy Playmate Jenny McCarthy and her son, Evan, who is autistic. Too much information? In a celebrity-obsessed culture, this is all common knowledge, just another headline in the grocery-store checkout line. You'd think it might be annoying to have every aspect of your personal life on public display, but Carrey doesn't take that bait.
"Nobody wants to hear a celebrity complain about their privacy,'' he says.
"It's whatever it is. There are times when that's hard and it's a pain in the butt, and there are times when it's just, you know, who cares? I get to do some amazing stuff. I get to do really fun stuff. So life is good."