Star Wars

Star Wars is a science fiction franchise originally developed from the 1977 film Star Wars directed by George Lucas. It has been referenced numerous times on the show.

References

Mr. Burns is sometimes introduced in certain episodes (like in "A Star Is Burns") while the "Imperial March" music associated with Star Wars villain Darth Vader plays in the background.
In "Old Money" Darth Vader is one of the people waiting in line to ask Abraham Simpson for money.
In "I Married Marge" Homer and Marge leave a film theater in 1980 after a showing of The Empire Strikes Back. Homer notes: "Who would have known that Darth Vader is Luke Skywalker's father?", angrying the crowd behind him, still waiting in line to see the film. He later calls Marge as pretty as Princess Leia and as smart as Yoda.
In "Lisa's Rival" Ralph Wiggum wins a diorama contest simply because he put some packaged Star Wars action figures, including Chewbacca, Luke and Obi-Wan, in a box. Principal Skinner turns out to be a big Star Wars fan and names him the winner.
Chewbacca is one of the aliens in the police line-up in "The Springfield Files".
In "'Round Springfield" Darth Vader is one of the characters appearing in the sky to talk to Lisa. (The other two are Mufasa from The Lion King and James Earl Jones saying: "This is CNN". The voices of Darth Vader, Mufasa and the CNN voiceover were originally all done by actor Jones. He has guest starred on the show three times, however on this occasion the voices are provided by Harry Shearer.
Mark Hamill (who plays Luke Skywalker in the Star Wars series) guest starred in the episode "Mayored to the Mob". In the episode he is forced to continue playing his famous role and sing a song called "Luke, be a Jedi Tonight" in a parody of "Luck be a Lady Tonight" by Frank Sinatra. While Homer is fighting Luke advises him to "use the forks" in a parody of "use the force" from the Star Wars films. On an advert for the sci-fi convention, C3-PO and R2-D2 are described as "the gay robots from Star Wars".
Yoda performs the leprechaun and gypsy's wedding ceremony in "Treehouse of Horror XII".

In "Bar t Has Two Mommies" Marge makes a Darth Vader mask and claims to be "Star Wars".

In "My Big Fat Geek Wedding" the Simpsons family tries to stop Comic Book Guy's Klingon wedding (in this case a Star Trek reference) with Mrs. Krabappel in a sci-fi convencion, where we can see three fans wearing Star Wars costumes: Chewbacca, C-3PO and Darth Vader.
In the simpsons Super Spactacular issue #6, Darth Vader and Jango Fett are seen at the comic book convention.
In the Couch gag of Sex, Pies and Idiot Scrapes, The Simpson's get froze into Carbonite, and Boba Fett carry's them away.