The Clones Quirk allows Ectoplasm to release ectoplasm from his mouth and shape it into clones of himself.
He can create up to thirty clones at a time, unless he's in a good mood (like after singing karaoke) where he can create thirty-six. The clones themselves can be destroyed through one strong blow, but only Ectoplasm can choose to dispel them otherwise.
- Forced Internment Giant Bites (強制収容ジャイアントバイツ Kyōsei Shūyō Jaianto Baitsu?): Ectoplasm releases a large amount of ectoplasm from his mouth and transforms it into a giant clone of himself. The giant Ectoplasm clone then overwhelms and traps the enemy with a bite. He first uses this against Fumikage Tokoyami and Tsuyu Asui during their final exam. 
- Ectoplasm - Wikipedia article about the fictional substance Ectoplasm creates with his Quirk, which serves as his namesake.
- Ghost - Wikipedia article about the constructs that Ectoplasm can create.
- Cloning - Wikipedia article about the process Ectoplasm's Quirk was based after.