Thomas and Twilight Sparkle's Adventures of The Lego Batman Movie is an upcoming Thomas/MLP:FIM/Warner Bros. crossover to be made by Hiatt Grey. And is is the sequel to Thomas and Twilight Sparkle's Adventures of The Lego Movie.
During a mission to prevent The Joker from destroying Gotham City, Batman hurts his arch-rival's feelings by telling him he is not as important in his life as Superman or Bane, leading Joker to seek revenge on him. The following day, Batman attends the city's winter gala as his alter ego, Bruce Wayne, to celebrate the retirement of Commissioner Gordon and the ascension of his daughter Barbara as Gotham's new police commissioner, but is infuriated when she announces her plans to restructure the city's police to function without the need of Batman. Without warning, Joker crashes the party with the rest of Gotham City's villains, but has all of them surrender to the police, making Batman soon realize that he is no longer relevant to the city's safety.
However, he quickly suspects Joker is planning something, and decides that the only solution to stop him is to banish him into the Phantom Zone. Before Batman can make plans to recover the technology that Superman uses to vanish criminals to the Zone, Alfred intervenes and advises him to take charge of Dick Grayson, whom Bruce had unknowingly adopted as his ward during the gala. With some convincing, Batman takes him under his wing as Robin, and the pair manage to recover the Phantom Zone Projector from the Fortress of Solitude, before breaking into Arkham Asylum and using it on Joker. Annoyed at his reckless actions, and suspecting Joker wanted this, Barbara locks up Batman and Robin. But while the Projector is being moved into evidence, Harley Quinn steals it back and uses it to free Joker, who unleashes numerous non-DC villains trapped within the Phantom Zone to cause havoc on Gotham, including Lord Voldemort, King Kong, and Sauron.
Realizing the city needs him, Barbara releases Batman and Robin and reluctantly teams up with them and Alfred to stop Joker. Batman soon finds himself able to trust and rely on the others, allowing them to defeat Sauron, but upon reaching Wayne Island, he ditches the team out of fear of losing them like his parents, before confronting Joker alone. Upon seeing that Batman will never change, Joker zaps him to the Phantom Zone, where he witnesses the harm he has caused to everyone because of his selfishness, and fears for the safety of Robin, Barbara and Alfred when they decide to come to his aid. Making a deal with the Zone's gatekeeper, Phyllis, to bring back all the villains in exchange for returning to Gotham, Batman arrives to save the trio and admits to his mistakes, requesting their help to save the day.
Seeking to stop Joker from setting off bombs at the city's Energy Facility, which would cause a faultline beneath it to open up and send Gotham City into the infinite abyss beneath it, Batman and his allies, along with the city's villains after they felt neglected by Joker, work together to send back the escaped villains into the Phantom Zone. However, bombs stolen from the Batcave by Joker manage to detonate and rip apart the city. Realizing how to stop the city being destroyed, Batman reluctantly convinces Joker that he is the reason for being who he is. Working together, Batman, Joker, their allies, and the city's inhabitants, chain link themselves together and reconnect the city's plates, saving Gotham City.
Once Gotham City is saved, Batman prepares to be taken back into the Phantom Zone to fulfill his bargain with Phyllis, only to be rejected by the gatekeeper after she saw how much he changed to save everyone. Batman allows Joker and the rest of his rogues gallery to escape with the confidence that when they return, they'll be no match for the combined team of himself, Robin, Barbara, and Alfred.
- Knockout, Puffer, Dolphy, Rachel, Mighty Joe, Daylight, Jenny, Pete, Kevin, Morley, Blitzer, Dile, Blythe Baxter, Zoe Trent, Pepper Clark, Penny Ling, Vinnie Terrio, Sunil Nevla, Minka Mark, Russell Ferguson, Gail Trent, Mitzi, Buttercream Sunday, Sugar Sprinkles, July, and Team Griffin/Eeveelution guest star in this film.
- The storyline continues in Thomas and Twilight Sparkle's Adventures of The Lego Ninjago Movie.