The terms Unknown (謎の男 Nazo no Otoko , lit. "Enigmatic Man") or ??? may refer to a number of characters in the Kingdom Hearts series.
- Xemnas in Kingdom Hearts Final Mix.
- Marluxia in Kingdom Hearts Chain of Memories.
- Riku in Kingdom Hearts II and Kingdom Hearts 358/2 Days.
- Xion in Kingdom Hearts 358/2 Days.
- Data-Roxas in Kingdom Hearts coded.
- Xehanort in Kingdom Hearts Birth by Sleep and Kingdom Hearts 3D: Dream Drop Distance.
- The Master of Masters and Luxu in Kingdom Hearts χ.