This is a 1.11 /summon command that summons a headless horseman!
Note: Minify the command to avoid issues :)
Killer Vindicator
A bunch of awesome commands part 14
THE ULTIMATE GUARDIAN
More superheroes in Minecraft ONE COMMAND
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)