Springtrap

Springtrap is the name given to the SpringBonnie suit William Afton died in.

Five Nights at Freddy's 4
While Springtrap himself isn't present in FNaF4, the minigames show multiple different SpringBonnie suits. One of the kids in the neighborhood also has a SpringBonnie plush named "Plushtrap". The plush is also part of a separate minigame used to skip hours in the next night.

Sister Location
Upon completing the Golden Freddy preset in Sister Location: Custom Night, the player is treated to a cutscene of Michael Afton monologuing over footage of Fazbear's Fright post-fire, saying that he's going to find his father. At the end of the cutscene, Springtrap can be seen emerging from the right side, appearing even more withered than before.

Freddy Fazbear's Pizzeria Simulator
A new version of Springtrap is one of the salvageable enemies in Pizzeria Simulator, referred to as Afton (or Scraptrap by fans). He seems to have mastered control of the suit and is even capable of speech, compared to only being able to moan in FNaF3. The animatronic itself also seems to be made from parts of different ones, with more bones and wires around him. His skull oddly looks completely different from before, thought it might be a casing rather than the skull itself.

Ultimate Custom Night
Both Springtrap and Afton return for Ultimate Custom Night. Springtrap makes his way towards the front vent opening, he will appear at the opening to indicate he's about to attack, and the player must close the vent door to send him back where he started. He can also show up in the FNaF3 office as an easter egg.

Afton attacks only once per night, at random time, he will cause noise and flickering lights to indicate the player must close the side vent before getting a jumpscare.