Black Boo

Black Boo is a Boo found only in Super Mario Bros. Deluxe. In the You vs. Boo mode of the game, Mario will encounter Black Boo as an opponent to race. After Mario competes and wins against Red Boo enough times, Red Boo will forfeit, and Black Boo will enter the competition. Black Boo is the quickest Boo in the game and will match the player's best time, making it the hardest opponent.

Trivia

 * Due to being black with yellow eyes, the Black Boo incidentally resembles the Bomb Boo enemy, which would debut eight years later in Super Mario Galaxy.