A Betus is an enemy found in The Hospital and The Cotton Alley. They are red slimes continuously crawling along whatever they can reach including platforms, walls, and ceilings. Like all enemies, contact with one will kill Meat Boy.
- The background music for the Hospital, "Betus Blues", is named after them.
- They have a striking resembles with the Lump enemies from The Binding Of Isaac, another game by Edmund Mcmillen