Sure, "The Simpsons" may have lost a step over the last...decade or so. Even still, it entices big star after big star to make cameos in its yellow Springfield universe. Some stars have been better than others, and then even some others have been outright crazy. To find the wackiest of the wacky, take a look at this list of the 25 craziest Simpson's guest stars of all time.

Albert Brooks.

The man with the most guest shots on the Simpsons, not counting recurring characters. His best role? Hank Scorpio in the episode "You Only Move Twice."

Bette Midler.

The Divine Miss "M" is at her crazy best in Season 4's "Krusty Gets Kancelled.

Kelsey Grammer.

The man who was Frasier has turned in countless crazy performances as Sideshow Bob.

Michael Jackson.

What was so crazy about his role in "Stark Raving Dad?" Maybe the fact that he did it under the name "John Smith," as if no one would know it was him.

Steve Sax.

Poor Saxy boy. Locked up in Springfield jail forever, all because he couldn't keep his mouth shut.

Leonard Nimoy.

Spock made a couple of  crazy appearances on the series. "The cosmic ballet goes on."

The Ramones.

"Hey I'd just like to say this gig sucks!" Luckily for them, Mr. Burns wasn't able to have them killed after the ruined his birthday.

Patrick Stewart.

The leader of the ancient, mystic society known as "The Stonecutters," Cpt. Picard played crazy with his trademark regal drawl.

Mickey Rooney.

Former biggest star in the world Mickey Rooney made a pretty good Fallout Boy. Jiminy jillickers!

Jeff Goldblum.

Jeff's stilted delivery made him right at home in the crazy world of Springfield.

Joe Mantegna.

"Fat" Tony D'Amico, the mafioso extraordinaire, wouldn't be the same without Mantegna's characteristic crazy voice.

Cypress Hill.

What was crazy about the legendary rap group's appearance on "The Simpsons?" How about ordering the London Symphony Orchestra for their Hullabalooza performance?

Rodney Dangerfield.

Who better to play Mr Burns' illegitimate son than the boorish and hilarious Rodney Dangerfield.

Jim Varney.

Ernest P. Worrell put his finely-tuned Shakesperean acting skills on display by playing the crazy carny "Cooter" in season nine.


Bono and Co. showed up in fine form, even giving Homer a chance to talk about waste management. Then they had their security team pummel him backstage.

Alec Baldwin.

Playing himself, Alec managed to be neurotic, funny, and crazy while he and wife Kim Basinger hid from the hordes of Springfield.

Mark Hamill.

In a fantastic guest appearance. Hamill played himself and managed to poke fun at his legendary status as Luke Skywalker.

George Carlin.

George did his "Hippy Dippy Weatherman" schtick in season ten, and added "Simpsons Guest Star" to his legendary resume.

Stephen Hawking.

The smartest man in the world is not immune to the crazy comedy of "Simpsons." His appearance was a surprise for many who never thought an astrophysicist would pop up on the show.

Mel Gibson.

In retrospect, Mel's remake of "Mr. Smith Goes To Washington" in his guest appearance was pretty tame compared to his modern-day craziness.

John Goodman.

The rotund veteran actor showed up as a sleazy biker in season 11, and his crazy voice work was among the highlights of the season.

Betty White.

The always great Betty White turned in a hilarious cameo as the face of a PBS pledge drive, viciously soliciting pledges from viewers like you.

Michael Keaton.

He's at his best when he plays crazy characters, so the role of convict/artist Jack Crowley in season 12 was perfect for the veteran character actor.

Pierce Brosnan.

As the creepy voice of a malevolent house (a la HAL in "2001: A Space Oddysey), Pierce put his James Bond gig on hold to crazy up the annual Halloween episode of "The Simpsons."

Phil Hartman.

Practically a regular cast member, Hartman's characters, Lionel Hutz and Troy McClure, were the undisputed kings of crazy. When Hartman died, so did a piece of the series.