King Boo is an enemy in the Mario series of games. He is a powerful ally of Bowser.

Luigi's Mansion

He first appeared in Luigi's Mansion as the final boss. When Luigi reached the roof, King Boo would appear in a Bowser disguise. Luigi had to use the Poltergust 3000 (vacuum) to suck up spiked balls that King Boo would throw out and throw them onto the Bowser head, which will cause it to fall off.

Using your vacuum on King Boo will make his HP decrease very fast. However, the Bowser head will be bouncing around, shooting ice at Luigi. If you get hit, the player needs to move the control stick back and forth to free Luigi from the ice. During the battle, King Boo will put the Bowser costume back on and the player has to repeat the process of throwing spiked balls in its mouth.

When its HP decreases to 200, King Boo will go back into the Bowser costume, although the head is on backwards. He'll do this for about ten seconds until he puts it on the right way.

Super Mario Sunshine

In Super Mario Sunshine, King Boo was boss for Episode 4 of the Sirena Beach level.

The battle field is on a spinning, round table divided into three different section. During the battle, you have to spray King Boo's tongue with water to activate a slot machine. It will either send out monsters, coins, or various fruit. When the fruit comes out, you need to find a hot pepper and throw it at King Boo's tongue. When you do that, he will light on fire. To damage him, the player needs to throw another fruit at King Boo. This process needs to be repeated three times, and once defeated, you will get a Shine.

Mario Kart: Double Dash!!

In Mario Kart: Double Dash!!, King Boo is a heavyweight character and his partner is Petey Piranha. Unlike all other Double Dash!! characters (except Petey), King Boo can use any special item.

Mario Party 5

King Boo is a playable character in the fifth installment of the popular Mario Party series. In this game, he is a regular character featuring no noteworthy attributes (except for his ghost appearance, of course).