Minecraft Dungeons:Skeleton Horseman

A Skeleton Horseman is an undead miniboss that can spawn randomly in various levels $$. When spawned, a music soundtrack plays.

Spawning
Skeleton Horsemen spawn on Adventure mode and above, and spawns randomly in groups in the Creeper Woods, the Soggy Swamp, the Pumpkin Pastures, the Cacti Canyon, the Desert Temple, the Dingy Jungle and the Overgrown Temple. In Apocalypse difficulty, they also spawn in the Redstone Mines, Highblock Halls and the Fiery Forge. They can also be found early on Default Mode uncommonly in the Cacti Canyon.

Behavior
Whenever a player approaches a newly-spawned Skeleton Horseman, it transforms into the Four Skeleton Horsemen and starts charging at the player. The Skeleton Horsemen also have high hit points and require constant damage to be defeated. They will sometimes shoot at the player with a Longbow, dealing extreme damage.

Trivia

 * Skeleton Horsemen's behavior and Boss fight theme style is similar to the Outlaw motorcycle club culture.