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 or Kingdom Hearts 358/2 Days
- Xion in Kingdom Hearts 358/2 Days
- Young Xehanort in Kingdom Hearts Birth by Sleep and Kingdom Hearts 3D: Dream Drop Distance
- Data-Roxas in Kingdom Hearts coded