Mutation

Mutant (異形 Igyō) -type (also called Heteromorphic-type) quirks are abilities that cause the user a permanent "abnormality" directly related to their power. Mutant-type quirks create bodily structures that grant the user more complex abilities that Emitter and Transformation quirks cannot safely provide. Often times they will bestow prehensile appendages that the user can control or add structures to pre-existing limbs to enhance pre-existing abilities. Mutant-type quirks even have the ability to channel certain aspects of their user through them in a similar manner to Emitter-type quirks.

Mutant-type quirks are also the only known type of quirk which can be passed down through generations without necessarily bestowing the corresponding ability, such as with Fumikage Tokoyami and his bird-like head that has nothing to do with his Dark Shadow, or Koji Koda's rock-like head which speaks nothing of his Anivoice quirk. They are the second most commonly inherited, after Emitter and followed by Transformation, and Psi types.