Phineas and Ferb

Milo Murphy's Law


 * In the episode The Phineas and Ferb Effect 2 of the characters of each shows end up crossing paths.

Marvel


 * In the crossover episode Phineas and Ferb:Marvel Mission the characters from marvel end up meeting.

Star Wars


 * An hour long crossover episode called Phineas and Ferb:Star Wars, also titled as Episode IVa: May the Ferb Be with You featuring characters from Star Wars.