Lady Imperia is the main antagonist of the episode "The Clockwork Smurf". She was King Gerard's aunt who desired to have her nephew's place as ruler of his family's kingdom when he was still a prince, and had him shut up in a dungeon for three years while claiming to the general public that he had been sick those three years. She had a male servant named Thorick who watched over her nephew to make sure he never escaped. On the prince's twelfth birthday, Imperia would proclaim to the subjects that Gerard's illness had taken a fatal turn so she could be crowned as queen while her nephew would be moved to a dungeon to rot away in obscurity for the rest of his life.
On the night before the coronation, however, Prince Gerard escaped with the help of Clockwork Smurf, who had sneaked his way into the dungeon by being inside the prince's pot of gruel. Fearing that her wicked plan would be undone, Imperia had Thorick and his troops search the forest for the prince and his "toy doll", but the two of them escaped and made their way to the Smurf Village. Imperia then left Thorick to watch the forest for any sign of Gerard while she returned to the castle.
On the day that she would be coronated as queen, Prince Gerard showed up again, dressed as a prince, and revealed Imperia's plot to the rest of the people, who then drove Imperia as well as Thorick and his men out of the kingdom, never to return.