Big Boo (boss)

The Big Boo is a boss who looks just like a translucent Big Boo, first appearing in Super Mario World. Despite the shared appearance, he acts differently from the normal enemies.

Super Mario World
In Super Mario World, the Big Boo is a hidden boss found only in the secret door of the Donut Secret House, which he inhabits. He has two normal Boos that accompany him in battle. The way he behaves is slightly different from that of other Big Boos: He floats in the air above and around Mario in a downward arching pattern rather than chasing him and does not even stop when being looked at. The Big Boo can be injured only when he is visible, so Mario has to throw a Grab Block at him at the right moment. Once hurt, he puts his hands on his face and becomes almost invisible so Mario cannot injure the Big Boo. He then moves somewhere else and reappears with his face uncovered. The Big Boo needs to be hit three times to be defeated. Mario or Luigi can touch the boss without being hurt but must be wary of the normal Boos. Once the Big Boo is defeated, a new path is revealed on the overworld, leading to the Star World. Unlike the Koopalings and Reznors, the Big Boo can be fought again at any time in the original without the use of the and  buttons on the map.

Super Mario Advance 4: Super Mario Bros. 3
The Big Boo reappears in the Game Boy Advance enhanced port of Super Mario Bros. 3. The Big Boo appears again as a boss whom Mario or Luigi has to fight against. He appears in the e-Reader levels Doors o' Plenty and Vexing Doors, where he plays exactly the same role as in Super Mario World, down to having two Boo allies for assistance. Unlike in Super Mario World, however, the Big Boo now has the ability to hurt the brothers on contact, though only while he is solid. Also, the player does not have the ability to kick blocks upward and must instead jump to the Big Boo's level to kick blocks at him in midair. While Mario or Luigi must use Ice Blocks instead of Grab Blocks, the method of defeating the Big Boo remains the same as in Super Mario World otherwise.

Physical appearance
The Big Boo's appearance rarely changes throughout his video game history. In his debut in Super Mario World, the Big Boo has white eyes shrouded in darkness (except the artwork shows his eyes to be black) and four vampire-like fangs (a characteristic shared by many Boos in the 16-bit era). His appearance stays the same through Super Mario World. In Super Mario World: Super Mario Advance 2, he is shown to be white, a change shared with the Big Boo species.

Traits and abilities
In addition to possessing the abilities of other Boos (including the abilities to teleport and to pass through walls), the Big Boo can become translucent and less visible so nothing can touch him. He can also reside in places where it is bright. Another difference between him and other Boos is that he does not fade away when he is defeated but appears visibly and falls down.

Trivia

 * In Super NES-era Player's Guides, the Big Boo enemy is known as "Big Blue Boo" to differentiate from the Big Boo boss.