It isn't exactly common knowledge that the hatbox ghost dates all the way back to the beginnings of Disneyland's Haunted Mansion. That's right, the ghost was in the attraction when it first opened.
The hatbox ghost was an invention of Yale Gracey (pictured above left). Yale was an Imagineer with a penchant for special events. Among other contributions he devised how to pull off the effect of the disappearing-reappearing ghosts in the ballroom scene. (Hint: contrary to popular opinion, it's not done with holograms)
The concept of the ghost's gag was to have his head disappear from his shoulders, then to reappear in the hatbox hanging from his left hand. The effect worked very well in the shop, however when located to it's place in the attic, the illusion was shattered, as the heads never darkened enough to "disappear". The problem was in its proximity to the doom buggy track. It was too close to the guests, thus the lighting could never darken enough to make the heads vanish. it was removed within the first couple days of operation.
Disney had long denied it's existence, having destroyed the figure long ago, as were the molds created for it. It wasn't until the Internet made it a legend, creating a cult following, when Disney began rolling out merchandise, T-shirts, collectible figures, and other merchandise. Fans started petitions, wrote letters, and made phone calls to Disney, demanding that hat box goes return to the mansion.
And that brings us to the present. Where lighting failed the ghost in the 60s, and newer technology made it possible today. Mr. hat box made his official debut last month in the mansion. He now resides just outside the attic window, and is magnificent.