The Simpsons just started its unprecedented thirtieth season on the air. This one is sure to include some special celebrity guest stars…which is old hat for the series. Here are some stories behind some Simpsons cameos. 

Leonard Nimoy 

One of the most famous episodes of The Simpsons is the 1993 installment “Marge Vs. the Monorail.” When Springfield receives a huge windfall, the town votes (against Marge Simpson’s warnings) to use it to install a monorail. It all goes horribly wrong of course, but at the least the celebrity on the maiden voyage is cool: Star Trek legend Leonard Nimoy. Writers crafted the script with Nimoy in mind, but assumed he wouldn’t want to do the show. Instead, producers pursued another Star Trek cast member: George Takei. He accepted, but had to back out when he remembered that he was a board member of the Southern California Rapid Transit District and didn’t want to publicly badmouth monorails. So, producers asked Nimoy…and he said yes. 

Michael Jackson 

The Simpsons was a white-hot cultural phenomenon in its first season, attracting even celebrity fans. The biggest musical star in the world in 1991, Michael Jackson, was such a fan of the show that he called up producers and asked if he could be the show. Staff happily obliged, and writers cooked up “Stark Raving Dad.” Homer Simpson lands in a mental institution (because he wears a pink shirt to work) and meets an overweight, Caucasian man named Leon, who believes himself to be Michael Jackson. He goes home with Homer, and helps Bart write a song celebrating Lisa’s birthday. In the credits, the role of Jackson is credited to “John Jay Smith,” but Leon really sounded like the King of Pop. Jackson did provide the speaking voice for Leon, but the singing was done (for contractual reasons) by an imitator named Kipp Lennon. 

Paul and Linda McCartney 

In the 1995 episode “Lisa the Vegetarian,” Lisa Simpson becomes, well, a vegetarian. She’s persuaded in her decision by a meeting with probably the two most famous non-meat-eaters in the world: Paul McCartney and Linda McCartney. (They explain that if their song “Maybe I’m Amazed” is played backwards, it reveals a recipe for lentil soup.) The McCartneys only agreed to guest star on the show if Lisa stayed a vegetarian for the duration of the show. After 23 years, The Simpsons is still on the air, and Lisa remains a vegetarian. 

Do Not Play Ball  

The 1992 episode “Homer at the Bat” finds Homer sitting on the bench at company softball games when Springfield Nuclear Power Plant owner Montgomery Burns fills out the team’s roster with Major League Baseball ringers: all of them all-stars, future Hall of Famers, and/or World Series champions: Wade Boggs, Ken Griffey Jr., Roger Clemens, Steve Sax, Ozzie Smith, Jose Canseco, Mike Scioscia, Don Mattingly, and Darryl Strawberry. All played themselves, because who wouldn’t want to appear on The Simpsons? A number of big leaguers, actually — Nolan Ryan, Ryne Sandberg, Carlton Fisk, and Rickey Henderson turned down the offer.