2) Teenage Mutant Ninja Turtles
Yes, the Dark Knight really has met those heroes in a half-shell. In 2016’s Batman/Teenage Mutant Ninja Turtles, the Turtles and their enemy Shredder are transported to the DC universe, where they land in Gotham and team up with Bats to take down a number of his rogues gallery. Batman even shares a pizza with Michelangelo!
Despite – or maybe – because of the total incongruity of this crossover, the miniseries proved so popular that it produced a spinoff. It was called Batman/TMNT Adventures, which ingeniously crossed over the Batman: The Animated Series‘ Batman with the characters from the TMNT animated series.
This one becomes even more meta when you remember that the Turtles were originally created as a parody of Daredevil. So, in theory, this is a crossover between a team of spoofs of a gritty, dark superhero and the grittiest, darkest superhero of them all.