King Boo

King Boo is the king of the Boo's, and Luigi's arch nemesis. He despises the Mario Bros., but hates Luigi more. This hatred is more vicious that Bowser and Mario's rivalry. King Boo has great Magical Powers, and becomes stronger if there are more Boos in the area. King Boo is allied with the King of the Koopas, Bowser, and is best friends with Petey Piranha. Also note that King Boo's ambitions to take over Sarasaland are similar to Bowser's ambitions towards the Mushroom Kingdom. Since appearing in the 2001 GameCube launch title Luigi's Mansion he has become a boss in the Mario Kart DS and playable for the Wii edition. He has also been a boss in Mario Party 9 and in the Mario and Sonic series. He is the main antagonists of the Luigi's Mansion series.