Minecraft Haters are...well, people who hate Minecraft. As a result, they in return are hated by Super Minecraft Kid, and he expresses this by slaughtering all of the haters of Minecraft in his animated videos.
A Minecraft Hater appears in All Star Smashers as a Support Spirit, as a novice class, where you must fight Matthew Whitehead at SMK's Stage to obtain him. When fighting Matthew, he'll equip a Master Sword, and various hostile Assist Trophies will appear during the battle. Oh, and he hates Minecraft too.