Minotaur

The Minotaur is the bull-like beast you become after gathering three magical four-leaf clovers. It is brown with a dark brown stripe of fur on it's back, has large horns and tufts of hair on it's head and under it's chin. It's eyes also glow yellow.

You become temporarily invincible and start burning while a different theme plays in the background. Running into enemies kills them and you move faster than normal.

According to the encyclopedia entry, this beast lurks within every inhabitant of Hardland, and the more terrible the deeds of it's bearer the less in control they are of it.

Encyclopedia Description
"It is said that those who stumble upon the magical four-leaf clovers turn into minotaurs. This terrifying inner beast hides within every living creature of Hardland, and the more terrible the deeds of its bearer the less in control they are. There are tales of ancients having controlled this power and its form."

Minotaur/Beast Mode Forms
Every character has a different form when they become a minotaur/beast. Here are all the different forms of the minotaur/beast for characters.

John Gore - Becomes a minotaur.

Jerry Gore - Becomes a minotaur. Has an eyepatch on his left eye and a moustache.

Zombieville Guy - Yellowed zombie with stitches

Hook Champ - Becomes a large skeleton.

Sway's Lizzy - Becomes a giant lizard with horns

Sway's Ninja Man - Demon with two scimatars

Evan Hsu - Evan with red eyes

Enviro-Bear - Large bear

Xmas Gore - Minotaur with santa hat

Sensei Evan - Large Sensei Evan

Gangster Gore - Minotaur with top hat

White Gangster Gore - White minotaur with a blood stained coat and tophat

Kid Gore - Smaller/younger minotaur

Santa - Devil santa

Easter Bunny - Larger Easter Bunny

Zombie Gore - Zombie Minotaur with darker fur

Undead Jenny - Moose with chainsaw

Grandpa - Zombie Grandpa

Grandma - Zombie Grandma

Elder Gores- Beast mode of which ever character you are playing as

Emperor Penguin- Large penguin with long jaw of serrated teeth

Penguin Mob- Emperor penguin's beast mode and red tinged mini penguins

Trivia

 * Although the encyclopedia entry says: "It is said that those who stumble upon the magical four-leaf clovers turn into minotaurs", very few characters actually turn into minotaurs, especially special guest characters. However, the entry also says: "This terrifying inner beast hides within every living creature of Hardland", meaning that only residents of Hardland turn into minotaurs, which could also mean that non-Hardlanders are affected by the clovers differently.
 * Hook Champ's beast mode form being a skeleton may be a reference to becoming a skeleton when you die in Hook Champ.