Aggressive Mobs

Put on your best armor and craft your strongest sword, and venture out into the darkest caves and coldest nights.
They are waiting for you.

Skeletal Knight

This bony warrior quickly cuts down foes with weak armor. They may not have the coordination of zombies, but they are faster, tougher, and meaner.

Angry Ghosts

Unlike regular ghosts, angry ghosts do not disappear when exposed to light and will attack on sight.
Angry ghosts come in different variants depending on the biome they spawn in. Each apply a different effect on hit.
Specter: Forests and taigas. Applies the weakness effect on hit.
Haunt: Plains. Applies the unlucky effect on hit.
Wraith: Deserts, badlands, and savannas. Applies the hunger effect on hit.
Phantasm: Mountains. Applies the mining fatigue effect on hit.
Shade: Jungles, dark forests, and swamps. Applies the blindness effect on hit.
Banshee: Snowy biomes. Applies the slowness effect on hit.
Nightmare: Nether. 50% chance to deal extra damage.

Ice Cube

These living blocks of ice wander the frozen terrains of the Overworld. They are born with a chilling hatred for their molten cousins that dwell in the Nether.

Maw

A large inhabitant of the Nether. They consist of a large jaw and an extended tongue, as well as a perpetual hunger for flesh. Maws that kill its target will eat it and gain a regeneration buff. Maws will not try to eat zombie pigmen because they have tried in the past and it wasn't a good idea.

Maws sometimes drop their tongue when killed, which is still very much alive. Right-clicking a bone block on its top side will attach the tongue to it and spawn a friendly maw. While friendly maws do not attack players, they still hunger and will attempt to eat nearby mobs that would pose a threat to the player. Also, they will still eat other maws so don't place them next to each other.
Friendly maws will drop their tongue if right-clicked with a gold nugget. This allows them to be moved elsewhere, however another bone block will be needed. Right-clicking a friendly maw with any meat item will heal it.