They appear as headless version of the Gaper with a bloody neck.
Pacers typically wander around blindly in an area, and have a low amount of health. This makes them of little threat to the player unless getting contacted.
- They can be spawned by Mr. Maws and Gapers. They are also spawned by Mom during the boss fight.
- They appear in the original game.
- Their Japanese name, Pēsumēkā, translates to "Pacemaker".
- A champion Pacer will maybe spawn in rooms that there is already Pacers (by replacing the normal one by a champion one) or by killing a champion Gaper / Frowning Gaper / Mr. Maw (killing a normal one will result in a normal Pacer or, in Mr. Maw's case, a Maw can spawn).