This article is rated PG-13, meaning it contains content that may be inappropriate for readers under the age of 13.
- Tom Holland as Peter Parker/Spider-Man
- James Earl Jones as Darth Vader
- Robert Downey Jr. as Tony Stark/Iron Man
- Logan Lerman as Daniel Fenton/Danny Phantom
- Saoirse Ronan as Megan Stark/Miss Martian (foster daughter of Tony Stark)
- Ewan McGregor as Obi-Wan Kenobi
- Ezra Miller as Barry Allen/Flash
- Adam Driver as Ben Solo/Kylo Ren
- Grant Gustin as Luke Skywalker
- Mark Ruffalo as Bruce Banner/The Hulk
- Ray Park as Darth Maul
- Ray Fisher as Victor Stone/Cyborg
- Ian McDiarmid as Emperor Palpatine
- Vin Diesel as Groot
- Bradley Cooper as Rocket Raccoon
- Liam Hemsworth as Boba Fett
- Chris Hemsworth as Gree Turban/Stormtrooper Commander Gree
- Elizabeth Olsen as Leia Organa
- Chris Evans as Steve Rogers/Captain America
- Chris Pratt as Peter Quill/Star-Lord
- Alden Ehrenreich as Han Solo
- Oscar Isaac as Poe Dameron
- Frank Oz as Yoda
- Felicity Jones as Jyn Erso
- Peter Mayhew as Chewbacca
- Donald Glover as Lando Calrissian
- Zoe Saldana as Gamora
- Guy Henry as Grand Moff Tarkin
- Ben Mendelsohn as Orson Krennic
- Michael Keaton as Adrian Toomes/Vulture
- Michael Mando as Mac Gargan/Scorpion
- Bokeem Woodbine as Herman Schultz/Shocker
Tony Stark is taking his adopted teenage daughter Megan to see Star Wars: The Last Jedi. After the movie, they walk home. They run into Peter Parker, who was also at the movie. They walk to Ultimate Tower, where they witness an oddly-shaped ship crashing. They run out of the tower and get to the ship. They find out that it is the Millennium Falcon, like from the movie they just watched. Then, Luke Skywalker, Han Solo, and other famous Star Wars characters walk out and say that someone is coming. Tony asks who, and Luke says "my father".
Tony brings the characters into the Ultimate Tower, and ask them why they crash-landed into Earth. Luke says that there is a super-weapon coming for Earth called "the Death Star". He also says that it is coming because an alien race called the Timebrokers messed up something in their universe causing an asteroid to destroy all the planets. Luckily, they were in the Millennium Falcon when it happened. But, to their dismay, the villains were in the Death Star, which wasn't destroyed (along with about a million TIE Fighters).
Tony tells Luke that they will find a way to defeat the Death Star. Luke asks how, and Tony tells him to watch. Tony got into his Iron Man suit and impressed Luke and the others. Then, Megan turns into a green-skinned alien. Peter got into his Spider-Man suit as well. Tony tells the characters to take the Millennium Falcon apart so they can build a bunch of spaceships before the Death Star arrives.
Tony calls in Star-Lord, Gamora, Flash, Cyborg, Danny Phantom, Hulk, and Captain America to help him save the world. They then build a bunch of star-ships out of the Millennium Falcon. They wait until the Death Star comes into orbit and attack it with their ships. They are arrested by the Galactic Police Force and are taken to a space prison where Rocket and Groot happen to be.
Megan and Gamora, who are cellmates, have a talk about what Megan should do about Danny Phantom, who she has a crush on. Megan says she just doesn't have the courage to ask him out, and Gamora says that she was afraid to say yes when Star-Lord asked her out for the first time, but she did it anyway (which is revealed to be false in Gaurdians of the Galaxy: Ultimate Heroes Edition). Megan says that when they get out of prison and destroy the Death Star, she will finally ask Danny out.
Danny and Spider-Man try to formulate a plan to break out, and then they run into Rocket Racoon, who grabs a gun and shoots the door, allowing all of the inmates to break out. The heroes allow Rocket and Groot to join the Ultimate Heroes for a brief period of time. They then get into their spaceships and go back up to the Death Star, where they try to formulate a plan.
The heroes make it in without being arrested by attacking the GPF and blowing them up with a Rocket grenade. They then split up to try to find Darth Vader, which Danny, Iron Man, Megan, and Spider-Man do. Darth Vader chokes Danny, Iron Man, and Megan while Spider-Man randomly escapes. Darth Vader tells Spider-Man this speech: "Look at you, look at me. We're both meant to be villains. Your closest family members- dead. My closest family members- dead. We're both meant to rule the galaxy. You can save them and be nothing but a kid wearing spandex, or you can join me and be the most important kid wearing spandex in the world!", to which Spider-Man replies "I'm not wearing spandex" and attacks.
Spider-Man is randomly thrown a blue lightsaber from Luke Skywalker and fights Darth Vader, while Danny escapes. He forms a green lightsaber and helps attack Vader. The two heroes fight Darth Vader and defeat him, when Luke Skywalker shows up, grabs Vader's lightsaber, and attacks, saying "You, you killed my father!" Spider-Man stabs Luke with the lightsaber and then Danny brings him back to life, but erasing his memory of the past 5 minutes.
The heroes decide to head home, and they send the Star Wars characters to New York City to find work and homes. They also go back to Ultimate Tower and relax for the rest of the evening.
The movie ends with Danny and Megan standing on top of Ultimate Heroes, talking. Once they notice that no one else is on the building, so Megan decides to finally ask Danny out. Danny says "what took you so long?" They kiss, and during the middle of the kiss, Spider-Man shows up on the roof.
In a post-credits scene, a man wearing a glass ball around his head shows up and tells the ghost of Vader how bad he failed.