Dipper & Mabel's Adventures of Phineas & Ferb: Mission Marvel is a special Gravity Falls/Phineas & Ferb crossover to be created by 12Adventureboy/12Adventureboy2. It is unknown when it will be made.
Marvel's Mightiest Heroes Spiderman, Iron Man, Thor, and Hulk enter Danville, Phineas and Ferb's territory after Dr. Doofenshmirtz's latest inator scheme accidentally removes their powers and immobilizes them. Now it's up to Phineas, Ferb, Dipper, Mabel, Dexter, Twilight Sparkle, and all their friends to team up with the Marvel Super Heroes to help them regain their powers and defeat Red Skull, Whiplash, Venom and M.O.D.O.K.- who are working together with Lil' Gideon, Hannibal McFist, Willem Viceroy III, Mr. Kat, Bill Cipher Mandark, Discord, and Dr. Doofenshmirtz to use his power-draining technology to create mayhem.
- Dexter (Dexter's Lab), Twilight Sparkle, Pinkie Pie, Rarity, Applejack, Rainbow Dash, Fluttershy, Spike (MLP), Wilt, Coco (Foster's Home for Imaginary Friends), Eduardo, Lil' Gideon, Hannibal McFist, Willem Viceroy III, Mr. Kat, Bill Cipher, Mandark, and Discord will guest star in this special.
- This is the first time Discord will guest star in a Dipper & Mabel Adventure film.
- Gravity Falls & Phineas & Ferb: Mission Marvel are both created by Disney.