The Simpsons' twenty-third season began airing on Fox on September 25, 2011 and ended on May 20, 2012. The show's 500th episode, "At Long Last Leave", aired on February 19, 2012.
Homer (Dan Castellaneta) befriends Wayne (guest voice Kiefer Sutherland), a reserved security guard recently hired by the nuclear power plant. Plagued by violent flashbacks from his past as a CIA agent, he must overcome his tortured nightmares to save Homer from a Ukranian terrorist. Meanwhile, Marge (Julie Kavner) fantasizes about being a contestant on “Top Chef” hosted by Tom Colicchio (guest voicing as himself), and the future of Springfield’s hottest “it” couple Nedna, Edna Krabappel (guest voice Marcia Wallace) and Ned Flanders, will be revealed after months of online fan voting and speculation.
Principal Skinner (Harry Shearer) challenges superintendent Gary Chalmers to take over Bart’s (Nancy Cartwright) education after one of Bart’s pranks leads to a school fundraiser debacle. Encouraged by Bart’s educational renaissance and fascination in President Teddy Roosevelt, Chalmers takes Bart and his band of “Rough Riders” on an overnight excursion but the school administration deems it an unauthorized field trip and fires Chalmers. Determined to get Chalmers’ job back, Bart and the boys hold the school hostage and they stand up for the teacher who made a meaningful impact.
In the spooky opener of the 22nd annual installment of “Treehouse of Horror,” Homer takes a dangerous dive into an isolated canyon on Candy Peak, but when a crashing boulder traps his arm, he channels Aron Ralston (guest voicing as himself) to save himself. In “The Diving Bell and Butterball,” the first of three hair-raising Halloween tales, a venomous spider bite leaves Homer paralyzed, but when Lisa discovers Homer’s ability to communicate through natural gases, he is able to express his love for Marge. The killer spells continue in “Dial D for Diddly,” when Ned Flanders, devout preacher by day, transforms into a cold-blooded vigilante by night. In the final terrifying tale, “In the Na’Vi,” Bart and Milhouse are assigned on a mission to access a sacred extract on a distant planet. They morph into the land’s indigenous one-eyed avatars, but when Bart finds love and an eternal mate abroad, he is caught in planet warfare.
Bart’s science fair project, a mechanical baby seal, outshines Lisa’s brainy asteroid model and quickly becomes a popular pet among the retirement home patrons. Meanwhile, Homer’s new and eager assistant, Roz (guest voice Jane Lynch), steals Homer’s job, forcing him to team up with Flanders to reveal her true colors and evil past.
Marge takes Bart and Lisa on a weekend excursion, and when an unexpected restaurant detour awakens their taste buds, fellow foodies Amuse Bruce and Fois Garth (guest voices Tim Heidecker and Eric Wareheim) inspire them to start their own food blog, “The Three Mouthketeers.” The threesome scores an exclusive reservation at Springfield’s premiere modern restaurant, but Marge has an unsettling dream during which Anthony Bourdain, Gordon Ramsay and Mario Batali (guest-voicing as themselves) lead her to reconsider inviting Homer. And later, Marge directs Homer to a different type of cooking lab where he gets into a bind with law enforcement authorities.
Lisa becomes disheartened when she learns the shocking truth behind the “tween lit” industry and her beloved fantasy novel characters, but Homer decides to cash in on the craze and forms a team to group-write the next “tween lit” hit, with the king of fantasy, Neil Gaiman (guest-voicing as himself), lending his expertise to the effort. After catching the eye of a slick industry publisher (guest voice Andy Garcia) at the Springfield Book Fair, the team gets an advanced copy of their work and discovers that the corporate lit business is a bigger operation than they imagined.
The Simpsons host a tastemaker party at their home to promote Absolut Krusty, Krusty the Clown's own brand of liquor. Mr. Burns takes notice of the party's success and decides to promote Homer to "Account Man" for the Springfield Nuclear Plant. Robert Marlow, a seasoned account veteran, takes Homer under his wing and shows Homer what the high life is like in the corner office. Meanwhile, Lisa introduces Bart to a new literary world which sparks his interest in reading classic novels, and when Homer's long hours at the office become the norm, a family vacation with Marge and the kids helps him realize that family always comes before work.
Krusty the Clown is stuck in a rut when the television network pulls his show from the air and his talent agency drops him as a client. After THE SIMPSONS introduce him to seasoned agent Annie (guest voice Joan Rivers), they are surprised to learn that Annie was Krusty’s very first agent. Despite their rocky relationship, Annie re-signs Krusty and crafts his career comeback. But when Krusty’s retro comedy show reboot is deemed a critical success, Krusty must decide to stay with his agent or side with the network executives.
It’s the most wonderful time of the year, and THE SIMPSONS flash-forward thirty years to find themselves in a tech-savvy, futuristic Springfield. Bart (Nancy Cartwright) and Lisa (Yeardley Smith) have children of their own and decide to spend the holidays as one big family at Homer (Dan Castellaneta) and Marge’s (Julie Kavner) house. Lisa and Bart turn to Homer and Marge for parenting advice and begin to realize that the apple doesn’t fall far from the tree.
Homer (Dan Castellaneta) lands his own political talk show after a video featuring his impassioned rant on poor treatment at the airport goes viral. As his talk show quickly gains popularity nationwide, Homer becomes the spokesperson for the Gravy Movement and the voice of America’s newest political party. But when ill-informed Homer is asked to select the next Republican nominee for President and officially endorses right-wing rock star Ted Nugent (guest-voicing as himself), Marge (Julie Kavner) and Lisa (Yeardley Smith) worry that Homer’s opinion and influence might be more powerful than he realizes.
As the mastermind and creator of the online social networking phenomenon SpringFace, Lisa (Yeardley Smith) is called to trial when Springfield's obsession with the site becomes chaotic and dysfunctional. Lisa explains that she created the site because she had no real friends, but the mass hysteria it creates forces her to realize that adding thousands of friends online does not compare to having real relationships. Later, Patty and Selma compete against the Winklevoss Twins (guest star Armie Hammer) in the rowing event at the 2012 Olympic Games.
After Moe (Hank Azaria) is heckled for not having any real companions, Moe’s best friend and beloved bar rag (guest voice Jeremy Irons) narrates his incredible thousand-year journey to Springfield. Beginning in the Middle Ages, the bar rag was loomed into a beautiful and ornate medieval tapestry and traveled around the globe through the hands of royalty before finding himself at Moe’s Tavern. Meanwhile, Bart (Nancy Cartwright) begs Milhouse (Pamela Hayden) for forgiveness after the two friends get into a tiff, and when the bar rag goes missing, Moe realizes that he has more friends than he thought.
Marge (Julie Kavner) and Lisa’s (Yeardley Smith) mother-daughter Valentine’s Day plans take a turn when Lisa meets Nick (guest voice Cera), an intellectual romantic who shares her passion for culture, history and literature. Lisa and Nick fall head over heels for each other in a fairytale romance and make a secret getaway to Mulberry Island to profess their eternal love. Meanwhile, Bart and Milhouse (Pamela Hayden) are inspired by the hosts of their favorite myth-exposing show (guest voices Hyneman and Savage) to debunk Springfield Elementary’s own legends.
Grammy Award-winning musician Alison Krauss records THE SIMPSONS theme song for the milestone 500th episode, and WikiLeaks founder Julian Assange guest-voices as himself. The Simpsons are evicted from Springfield and join an off-the-grid community outside of town. But when Homer (Dan Castellaneta) and Marge try to sneak back into Springfield, they are welcomed with hostility from their former friends and neighbors and begin to appreciate their new, more accepting home.
In order to get back at his dad, Bart goes undercover as a graffiti street artist and plaster's Homers's unflattering image all over springfield. But one night, Bart and Milhouse get caught in the act by established street artists Shepard Fairey, Ron English, Kenny Scharf and Robbie Conal, and to Bart's surprise, they invite him to exhibit his satirical artwork in his very own gallery show.
Karma gets the best of Homer after he gets his friends in trouble, and as a result, his bedwetting problem worsens. The family goes on a mission to infiltrate his dreams to search for clues in his subconscious to determine the source of his problem. But just as things take a dangerous turn in the dream, a figure from Homer's past appears, and he is finally reassured that the fond memories of his mother Mona remain alive, giving him just the right amount of reassurance to cure him of his problem.
Mr. Burns replaces all of his employees with robots—with one exception: Homer. This raises the unemployment rate in Springfield significantly, and leads to much misery. And it hits home to Homer, too, when robots attack him.
When Bart (Nancy Cartwright) is forced to chaperone Jimbo’s (Pamela Hayden) girlfriend to a movie, she ends up developing feelings for him, resulting in a whole bunch of trouble with the bullies at school. Meanwhile, Homer (Dan Castellaneta) is persuaded to buy a state-of-the-art treadmill, fully equipped with a television. When Lisa (Yeardley Smith) shows Homer that he can access television shows wirelessly, he develops an obsession with watching an old television show from the treadmill, but not actually working out, until Marge (Julie Kavner) decides to intervene.
When Bart sees a commercial for the ultimate cruise, he begs his parents for a family vacation. Low on cash, the only way they can go is if each family member sells one valuable. Once they're away, Bart is determined to make the vacation last forever. So he comes up with a plan to make sure they never have to return home.
Homer's head injury helps his love life.
When the town of Springfield discovers that Ned (Harry Shearer) and Edna (guest voice Marcia Wallace) have secretly gotten hitched, Marge offers to throw them a congratulatory reception. However, bringing everyone together makes them all realize that no marriage is perfect. Meanwhile, Edna tries to help Ned's children become more socially acceptable by changing some of the rules.
Lisa tries to reverse her status as one of the least popular girls in school by ghostwriting positive things about herself on the school blog. When her plan backfires, her social ranking plummets to a new low – until a psychic force tells Lady Gaga (guest-starring as herself) that Lisa needs her help. With Gaga’s assistance, Lisa and the entire town of Springfield realize that being yourself is better than being like anyone else.