Gold Ghost

The Gold Ghost is the first ghost Luigi encounters in Luigi's Mansion. One is first seen in the Foyer as a foggy cloud carrying a key, which then goes through a door into the Parlor. There, a group of them accost him, leading him to meet Professor E. Gadd. They later appear in the training mode in E. Gadd's hideout, where they chase Luigi but do not attack him, unlike the ones found in the mansion. They reappear countless times throughout the mansion, found in groups of two or more and can be hurt by any element.

A Gold Ghost cameos in several later Mario games. In Mario & Luigi: Superstar Saga and its remake, a Gold Ghost briefly cameos in Starbeans Cafe after the player brews the first drink where it scares Luigi, only to be sucked up by Professor E. Gadd upon entering.

In Mario Power Tennis, the Gold Ghost, as well as several other generic ghost species from Luigi's Mansion, appear on the Luigi's Mansion Court and in the minigame Terror Tennis. In Mario Super Sluggers Gold Ghosts appear in the unlockable stadium Luigi's Mansion. In Mario Party 8, Gold Ghosts cameo in the minigame Specter Inspector. The Gold Ghost also appears as a part of a trophy in Super Smash Bros. Brawl.

Gold Ghosts make an appearance in Mario Sports Mix as spectators in the sporting events.

In the Nintendo Land minigame Luigi's Ghost Mansion, the Mii attacking the other four Mii players use a Gold Ghost costume.

Greenies, found in Luigi's Mansion: Dark Moon, are the equivalent of the Gold Ghosts.

Reference
Spukgeist Fantasma arancione