Oobs are stronger enemies added to The Binding of Isaac: Rebirth. They first appear in Chapter 4.
It has a similar AI to Harbingers (Famine and War). When Isaac is not horizontal to it, it spawn 2 Brains. When Isaac is horizontal to it, it does a very fast charge that can cover the entire room at once.
- Oobs are also enemies from another one of Edmund's games, Super Meat Boy.
- Oobs are one of the few non-boss enemies to have over 100 health points.
- Oobs are the only enemies to have a Harbinger-styled charge attack. Same apply to their variant Black Maws.