Across 33 seasons, a movie, and a handful of shorts for The Tracey Ullman Show, The Simpsons has become so thoroughly enmeshed with the culture that you'd be hard-pressed to find someone who doesn't have an opinion on which season is best, when the show changed, who their favorite character is, or, more importantly, who their favorite guest cameo is.
From humble beginnings to the longest-running sitcom at well over 700 episodes, there are countless celebrity appearances on The Simpsons. While some have been forgotten by time, others stand with the best of their most iconic roles.
10 Willem Dafoe as the Commandant
It seems that Willem Dafoe is just about everywhere as of late. His intensity, his growl, is always a cause for celebration because the audience knows that he's going to give it his all. Even on The Simpsons as the Commandant at the military school where Bart and Lisa find themselves stranded, Dafoe turns what could be a pretty banal role into a formidable presence. As he berates the children and encourages them to do better, it makes the audience wonder why there isn't a TV show dedicated to Willem Dafoe being a drill sergeant, straightening out unruly youths in pursuit of the greater good.
9 Patrick Stewart as Number One
When it's accidentally discovered that Homer has a birthmark in the shape of the Stonecutters insignia, he is granted access to their secret society. Homer begins to drink from the cup, so to speak, and finds that his life goes a lot differently when he gets discounted rates from all of the other club members. From there, things go about as well as expected.
At first, Homer, "the chosen one," is given the royal treatment, but things quickly fall apart. At the head of the Stonecutters is Number One, voiced by none of than Captain Jean-Luc Picard himself, Patrick Stewart. Moonlighting as a cult leader, by day he works as a security guard at the local Star Trek museum. Stewart does a great job playing the straight man to Homer's comic buffoon and delivers what is remembered as an instantly iconic role.
8 Meryl Streep as Jessica Lovejoy
Before appearing as herself in the "Behind the Laughter" episode of The Simpsons, Meryl Streep lent her voice to the role of Jessica Lovejoy, the wayward daughter of the Springfield reverend. She couldn't be more unlike her father, and Bart finds out the hard way. Finding himself head over heels and in over his head, Jessica manipulates Bart into a series of increasingly daring antics.
Jessica remains a major figure in Bart's love life, and even though things don't work out for them in the end, it's just a lesson well learned. Jessica's behavior is a bit reductively explained as a way of seeking her father's approval, but it's a great cameo where Bart learns that he's not all that bad.
7 Dennis Franz as Himself as Homer
When Homer is accused of sexual harassment, the subsequent media frenzy takes on a life of its own. The episode plays like a series of vignettes critiquing the way that the media has a life of its own, taking hold of a narrative and then spinning various exploitative yarns to fuel its moneymaking machine. Among the many TV programs parodied in the episode, there's one including NYPD Blue's Dennis Franz – one of TV's greatest curmudgeons – appearing as a fictionalized version of himself. In the scene, Franz portrays Homer in the made-for-TV movie about his purported indiscretions. Franz leans into his fictional persona, and it's one of those great scenes that's all-too-brief, but stands out for its pure comic excellence in execution.
6 John Waters as John
John, voiced by none other than the Pope of Trash himself, John Waters, is the proprietor at Cockamamie's, a kitschy antique shop. When Marge finds out that an item she's trying to sell is worthless, she finds herself charmed by John, and soon the Simpson children are also swayed by his charms. When it's revealed that Homer's latent homophobia is keeping him from becoming close to John, the episode goes into dazzling new territory. Throughout the episode, Homer comes up against the limits of his own beliefs and we watch as his prejudices are stripped away. Who else but John Waters to deliver a shock to a backward system?
5 Gillian Anderson and David Duchovny as Dana Scully and Fox Mulder
Although the episode features a great cameo by Leonard Nimoy, who recounts the tale of "The Springfield Files," it is an episode dedicated to another Fox television show, The X-Files. Arriving in Springfield, the two supernaturally inclined FBI agents investigate a case of a strange glowing man with a trilling, angelic voice, who appears in the woods.
It is eventually revealed that the alien is none other than Mr. Burns himself, whose glowing condition is due to having undergone a routine treatment increase his life expectancy, naturally. Scully and Mulder, in an all-time great sequence, perform a series of tests on Homer, to find out whether or not he's telling the truth about the would-be alien visitor.
4 Glenn Close as Mona Simpson
Though The Simpsons has its fair share of emotional highs and lows, it's mostly known for having a gag-a-minute style. Part of the pleasure of rewatching the series is catching all of the little jokes that you might have missed the first time around. But sometimes The Simpsons does away with the relentless pacing and goes straight for the emotional gut punch.
Few episodes are better examples of that than the introduction of Glenn Close as Homer's mother, Mona. It's an episode that deals with the complexities of a mother's love. With fewer gags and more of an emotional arc, watching mother and son trying to reconnect despite an impossible situation is heartbreaking. The Simpsons rarely confronts heavy subject matter, but when they do, they know how to stick the landing.
3 Kirk Douglas as Chester J. Lampwick
When Bart meets a homeless man by the name of Chester J. Lampwick, he discovers that the man is none other than the creator of Itchy & Scratchy. Ousted from his own media empire, Chester has fallen on hard times. With the help of Bart, Lisa, and the comically inept lawyer, Lionel Hutz (voiced by Phil Hartman), Chester sues the studio to receive compensation for his work.
Immediately upon receiving the money, Chester buys a mansion made entirely of gold and forgets about Itchy & Scratchy. The Simpson kids, shocked that they could bankrupt the studio and forestalling any new episodes, have to then find a way to bring the show back to life.
2 Albert Brooks as Hank Scorpio
No other guest actor has appeared in such a wide array of Simpsons roles as Albert Brooks, but his best cameo is as the manic, would-be world dominator, Hank Scorpio. A charming James Bond-type villain, he comes across more like an upbeat, modern tech magnate than an overtly nefarious character.
It's part of Brooks' comic persona as an eager-to-please person that gives rich flavor to the character Hank Scorpio, who, for some reason or another, really takes a liking to Homer. It all comes to a head when government agents storm Scorpio's base, resulting in one of the greatest action sequences that The Simpsons ever had.
1 Kelsey Grammer as Sideshow Bob
Could there be any greater guest than Frasier himself? Probably not. Instantly iconic, and brought back time and again, Kelsey Grammer's Sideshow Bob is a wild-haired, clown-footed rage machine who finds himself thwarted at every turn by Bart and the rest of the Simpson clan. His inability to kill Bart always proves to be an entertaining experience.
Sideshow Bob is charming, theatrical, and known to break out into a show tune or two. It's the purr of Grammer's voice, able to go from soft-spoken soliloquy to a fit of maniacal laughter that makes this character such a memorable part of The Simpsons guest roster.