Vis

Vis are enemies most commonly found in The Depths. They are headless like Hoppers and have their entire torso cut open. When Isaac lines up with the Vis in a cardinal direction, it will fire a beam in that direction.

Double Vis
Added in the Wrath of the Lamb DLC for the original Binding of Isaac, the Double Vis appears similar to the normal Vis but has blood around its openings and a vertical gash in its back. They function identically to regular Vis, but they also fire a beam from behind.

Chubber
Chubbers, like Double Vis, were added in the Wrath of the Lamb DLC for the original The Binding of Isaac. They look identical to a Vis but have a maggot as their head. Instead of shooting the beam that regular Vis and Double Vis have, the Chubber shoots a Charger, similar to the Little Chubby Familiar, which can go through rocks. They can be found in the same locations as Double Vis; however, they are less common. The Charger it shoots does a full heart of damage, will destroy any tears in its way, and has a limited range. Once the Charger has reached this range, it will return to the Chubber.

If the Chubber is killed before the Charger has returned to its body, he will still return to the last location and will simply disappear upon touching it. The Charger can still damage Isaac during this time.

Killing the Charger with a Chaos Card will not transform the Chubber into a normal Vis. If the Charger is charmed when being fired, it will not deal damage to the Chubber when returning.

Using the on a Charger will render Chubbers unable to attack for the rest of the run.

Scarred Double Vis
The Scarred Double Vis behaves identically to the normal Vis but fires four beams in the cardinal directions.

Vis Versa
The Vis Versa behaves identically to Vis, but fires a purple homing at Isaac instead. In Gehenna, their appearance becomes black instead of white, and their becomes red.

Evis
The Evis behaves similarly in movement to Vis and its variants, but launches a string of guts at Isaac instead of.

If Isaac is hit, he doesn't immediately take damage, but is instead held by the whip and can't get any further away from the Evis while the cord gradually shrinks as Isaac is pulled in. He can still move at the same radius, but as soon as he gets closer, said radius gets smaller. The cord also has an elastic effect causing Isaac to bounce back closer to the Evis if he attempts to pull away. This lasts until the Evis is killed.

Trivia

 * In the original Binding Of Isaac, if a Vis or a Double Vis was a Champion, its would be colored.
 * Gluttony is a Vis with a head.
 * Similarly, Super Gluttony is a Double Vis with a large head.
 * The Cage can spawn Vis with a unique coloration but no change to their behavior.
 * Their designs are based on the Sisters Vis, which originated from Gish, one of Edmund McMillen's other games.
 * If a Chubber is a champion, only the Vis part is colored and the Charger stays the same.