Invisibility refers to objects and things not being seen in the game in some sense, especially:
- The partial invisibility power-up from the Doom games.
- The partial invisibility effect of the Doom games.
- The translucency effect in Heretic and other games.
- The invisibility power-up from Doom 3.
- Transparent graphic resources representing invisible objects.
- The property that makes things invisible (MF_NOSECTOR).