The King the Queen and the Duchess are three ghosts in the Haunted Mansion.
The three ghosts are seemingly Medieval indivisuals one of whom is dressed as a king, one a queen, and one supposedly as a Duchess.
The Haunted Mansion
In all versions of the Haunted Mansion, the trio can be found in the graveyard. The King and Queen play on a makeshift see-saw balancing on a tombstone as the Duchess plays on a swing hanging from a tree nearby.
In Marc Davis' original plans for the attraction, the King and Queen were meant to dematerialize as they reached the bottom of the see-saw. Both would be visible in the middle position and when one was at the top.
The Ghost Gallery versions of the characters are three party-goers who attended a Halloween costume party hosted by Mme. Tangerine in the graveyard of the Haunted Mansion. They all died due to the tea they drank having been tainted by the decomposed corpse of Gus Gracey who was rotting in the well where they drew their water for tea.
They are buried on the mansions grounds with epitaphs based off of their pun party aliases. This makes them composite characters with the inhabitants of the Pun Crypts.