The Blurb walks towards Isaac and fires a chaotic burst of tears if they get close. After firing their tears, they act like regular Gapers and chase Isaac, attempting to deal contact damage.
The Deep Gaper pops out of the water and chases Isaac. It has a chance to spawn with a Small Leech attached, which will detach when the Gaper is killed.
The Wraith chases Isaac. It is detectable only by its reflection and the ripples in the water, and the occasional lightning that makes them briefly visible.
The Coal Boy walks towards Isaac, periodically firing several hot rocks towards Isaac, some of which may be Coal Spiders. Hot coals linger and can hurt Isaac.
The Fanatic is a cultist which appears exclusively in the boss fight against the Heretic. At the beginning they are seen in a group of 5 on the edges of a large purple pentagram on the floor, chanting and kneeling towards the center as the Heretic emerges. They are covered with shields and can not be killed until the Heretic is done spawning. Once they are done, they will chase Isaac while shooting homing tears periodically. Upon death, they have a chance to turn into Pacers or Gushers like normal Gapers.