This mod adds many unhinged mobs, for example:

John is a hostile mob that spawns in the John Dimension and in dark forests, it leaps at the player and damages them.

The John Zombie is also a hostile mob that spawns in the John Dimension and in dark forests, it just acts like a normal zombie.

The Jogged is a passive mob that spawns in cherry groves, its gel is a good food source.
And more things.