Wither!
Note: Minify the command to avoid issues :)
Realy! do not do that!
Magic heads in one command
1.9 YOU WILL NEVER SEE SOMETHING LIKE THAT!
Herobrine in one command ! (Don't spawn him!)
Pet ENDER DRAGON!!!!!
Wither Storm Boss in ONE COMMAND
HEROBRINE COMMAND
HEROBRINE BOSS BATTLE (See YouTube for details)