Neil Patrick Harris -- Harold and Kumar Go To White Castle

When you're stoned to the bone and your numero uno priority is snacks, the last thing you expect to find is the star of Doogie Houser, MD wandering along the road in the dark. But that's exactly what Harold and Kumar experienced on their journey to White Castle. In one of the most talked about cameos of the mid-2000s, a high-as-a-kite on ecstasy NPH finds himself in the back of Harold and Kumar's whip, barking orders and talking crazy.

Bill Murray -- Zombieland

While cutting loose in someone else's house and blasting the theme from Ghostbusters, Tallahassee and Wichita encounter none other than zombie Bill Murray! Turns out it's just regular Bill Murray in zombie make-up because, you know, he likes to get around and blend in with the locals. Tallahassee freaks out because, well, because it's BILL MURRAY. They inhale some druggy smoke and end up reenacting a scene from Ghostbusters. It's a double whammy cameo and certainly one of the best on record! Legend has it that Bill Murray is one of the hardest actors to get in a film. Lucky for Zombieland and its viewers, Woody Harrelson has a far-reaching rolodex.

Kurt Vonnegut -- Back To School

What old-man college comedy is complete without a cameo? Maybe your dad wasn't as obsessed with Rodney Dangerfield as mine was, but, if he was, you might have noticed this literary luminary on the big screen. That's right kids, when charged with writing a paper on Vonnegut, Thornton goes straight to the source. Vonnegut arrives at his door, allegedly writes a paper about himself, and Thronton gets a failing grade. It's unclear why the author of such American classics as Slaughterhouse Five and Breakfast of Champions decided to take the cameo role, but I'm sure glad he did.

Lance Armstrong -- Dodgeball: An True Underdog Story

Long before the world knew the truth about Lance Armstrong, everyone believed we'd found a true American hero. During his reign as America's favorite cyclist, Armstrong lent himself and his advice to Peter La Fluer in an airport. This has always been one of my favorite random cameos. Turns out, it's even funnier now. "I'm sure this decision won't haunt you for the rest of your life," Armstrong sarcastically says. In the end, Dodgeball was a better career move for Vince Vaughn than performance enhancing drugs were for Lance Armstrong.

Elvis Costello -- 200 Cigarettes

Blink and you might miss this cameo. The English songster is referenced throughout this 1999 comedy. His music blasts in the background as the cast of characters attempts to assemble for a New Year's Eve party in New York City in 1981. He casually interrupts a sidewalk conversation between Courtney Love and Paul Rudd and later surfaces at Martha Plimpton's party, while the hostess is passed out. A man of few words, Costello's casual cool makes this cameo one of my all-time faves.

Bruce Springsteen -- High Fidelity

When you're going through the worst breakup for your adult life, it makes sense that you'd seek solace in your favorite music. For Rob Gordon, this impulse is overwhelming. More than just listening to tunes, he vividly imagines exactly what advice the Boss would give him as he tries to let go of his past loves. Rob's daydream makes for one of the most apt cameos in pop culture history.

Bob Barker -- Happy Gilmore

Paired together for a celebrity golf tournament, Bob Barker and Happy Gilmore engage in fisticuffs on the putting green. In Bob's defense, Happy is playing just terribly. Bob, who's accustomed to encouraging others in game play, simply can't stand to watch their names fall in the standings. The lower they drop, the more sarcastic Barker gets eventually devolving into direct insults. Hockey playing Happy attempts to settle the score the only way he knows how, a fight. What follows is one of the silliest and most memorable cameo fights of modern comedy.

Stan Lee -- Mallrats

The day your girlfriend dumps you in a letter is a rough day for any guy. To make matters worse, Brodie can't even get into the comic book store at his local mall to see his all-time favorite comic book writer, and real life father, Stan Lee. Brodie's buddy T.S. somehow convinces Lee to give him a pep-talk and some unsolicited dating advice. Though Brodie remains slightly preoccupied by the deeper truths behind his favorite superheroes, he seemed to get Stan's message of love.

Alice Cooper -- Wayne's World

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