Ghost

There are several types of ghosts in the Mario series, as well as things relating to them. As such, "ghost" could refer to:
 * Bat (ghost), a minor ghost from Luigi's Mansion.
 * Boo, a common ghost-enemy of the Mario series.
 * Boo Guy, a Shy Guy ghost appearing in Super Mario World 2: Yoshi's Island.
 * Bowling Ghost, a type of ghost found in Luigi's Mansion.
 * Bowser's Ghost Cologne, a brand of cologne that was used in Hotel Mario.
 * Caged Ghost, an enemy from Super Mario World 2: Yoshi's Island that grow from drainage grates in the floor.
 * Dangling Ghost, a type of Caged Ghost in Super Mario World 2: Yoshi's Island that dangles from the ceiling.
 * Eerie, a type of ghost found in Super Mario World.
 * The Elemental Ghosts from Luigi's Mansion.
 * Garbage Can Ghost, a type of ghost found in Luigi's Mansion.
 * The Ghosts from the Mario Kart series, which are recordings of the player's driving performance.
 * The Ghost from Super Mario Galaxy 2, a type of Luigi ghost.
 * The boss and enemy Ghosts from Wario Land II.
 * Ghost Houses, large buildings where various Boos live.
 * Ghost T., a deceased Toad in Paper Mario: The Thousand-Year Door.
 * Gold Ghost, an orange ghost appearing in Luigi's Mansion.
 * Grabbing Ghost, a type of ghost found in Luigi's Mansion.
 * Lantern Ghost, a lantern-carrying ghost from Super Mario World 2: Yoshi's Island.
 * Big Lantern Ghost, the mid-boss of the Shy Guy's Toy Box chapter in the game Paper Mario.
 * Phantom, a synonym for ghosts.
 * Portrait Ghost, a major type of ghost found in Luigi's Mansion.
 * Roger the Potted Ghost, a boss character from Super Mario World 2: Yoshi's Island.
 * Skeleton Ghost, a skeleton ghost appearing in Luigi's Mansion.
 * Shy Guy Ghosts, a ghost Shy Guy appearing in Luigi's Mansion.
 * Sparks, spiky ghosts that appear in Luigi's Mansion.
 * Sunken Ghost Ship, the gate to the Valley of Bowser in Super Mario World.