Ghosts are replays of previous Time Trial attempts. As such, they only appear in that mode. They have appeared in most games in the series. Ghosts appear as semi-transparent characters and behave as players who used them. These ghosts cannot be touched and pass through karts and obstacles.
In Mario Kart 64, Ghosts were saved on Memory Cards. As a result, Ghosts cannot be saved in the Virtual Console version of the game. In most games, a player can save a Ghost per track.
In Mario Kart DS and Mario Kart: Super Circuit, players can download a friend's Ghosts wirelessly or through a Game Boy Advance connector, for two Ghosts per track. In Mario Kart Wii, they can download Ghosts from the Nintendo Wi-Fi Connection, including Rival Ghosts, Champion Ghosts, and Friend Ghosts.
- Main Article: Staff Ghosts
Introduced in Mario Kart: Double Dash!!, there are Staff Ghosts. These ghosts are made by Nintendo's staff. Throughout the games, some tracks have reused characters, such as Mario for Mario Circuit, or Bowser for Bowser's Castle.
In more recent Mario Kart games, if the player can get a fast enough time, they will unlock a Ghost made by one of the developers who made the game. These times are very tough as they use the best tricks for their track. Mario Kart DS included one unlockable Ghost per track, which is the equivalent to an Expert Staff Ghost.
In Mario Kart Wii and Mario Kart 7, there are two developer Ghosts per track, one called Staff Ghost, and the other called Expert Staff Ghost. The normal ghost can be easily beaten with practice on the track. However, the expert ghost uses every trick he or she knows, including mushrooms being used at the right time, stunts being performed everywhere, and drifting right at the edge of the track. In Mario Kart 8 Deluxe, there are two staff ghosts, one for 150cc, and one for 200cc.