Mask Gates are eagle-head gates found in Super Mario Bros. 2. They are stationed at the end of each level, attached to walls. Entering a Mask Gate transports the player to the next level, or into the room of the current world's boss. To open a Mask Gate, the player must pick up a Crystal Ball, which is either placed out in the open or must be surrendered from an attacking Birdo.
All Mask Gates are harmless to the player, except for one, which is stationed in Wart's Castle. The Mask Gate here detaches itself from the wall, and begins to chase the player in a manner similar to a Phanto. The player must attack using the Mushroom Blocks in the vicinity to temporarily stun the Mask Gate to provide entry into Wart's throne room. However, if the player doesn't enter into the Mask Gate when it's stunned, it'll eventually reanimate itself again.
What appears to be a Mask Gate appeared in the episode "Too Hot to Handle" of The Super Mario Bros. Super Show!. Although King Koopa leaped into the Mask Gate at the climax of the episode to make his getaway, it appeared to be inanimate and was made of stone.
A Mask Gate has appeared in volume 8 of Super Mario-Kun. This Mask Gate is similar to the one near Wart's Castle since it attacks when Mario tries to enter through it. As in the games, Mario throws a Mushroom Block to have it allow him, Luigi, and Yoshi to enter Wart's Castle.