- For the player-placed, obtainable version, see Obsidian Brick Wall.
Obsidian Brick Wall is a type of wall commonly found in the Underworld as the wall of Ruined Houses. It is lighter in color than the placed version, and will not be usable for NPC houses, or for stopping enemy spawning. When destroyed, it drops the Obsidian Brick Wall item, which the player can use to place the darker-colored variation. This placed variation can be used for housing and enemy-preventing.