The Mistress of Evil was created by imagineer Rolly Crump to be one of the many curiosities contained within the Museum of the Weird. She would have lurked in the balconies of the attraction. Imagineer Rolly Crump described the show-scene as the following:
- ““The Mistress of Evil was another character I came up with, and I was going to have her appear in an archway, up on a balcony. There was going to be flames around her, but made out of China Silk, and lit it just right, it looked like the real thing. She would be lifted up in the air, and she’d open her arms real wide and start screaming like Maleficent did. Just really creepy and weird stuff I had her doing.””
- ―Rolly Crump, It's Kind of a Cute Story
Ultimately the Museum of the Weird attraction went unbuilt and the Mistress of Evil to date has not yet made her debut in Disney Parks.
The head of the Shadow Society, Despoina desires immortality above all else. Aligning herself with an evil entity known as the Reaper King, she's been able to cheat death for centuries by being granted an impenetrable armor made of her own shadow by the Reaper King. She has long sought to release the Reaper King from his imprisonment in the Coffin Clock and was able to attempt such an effort by capturing the Keeps to ransom them and force their children to do the job. As it turns out, this was an elaborate and risky ruse by the Keeps to force the Shadow Society out of hiding to allow the Wardens to take care of them once and for all, though the Wardens did not approve of putting the Coffin Clock's location at risk. When the Coffin Clock is taken from its hiding place, a battle ensued between the Shadow Society and the Wardens. When the Reaper King's countdown ended, it emerged to punish his followers for taking so long. This included stripping Despoina of her immortality. Though the Reaper King is sealed away again, the depowered Despoina escapes, though her ability to threaten the world is diminished.
- Despoina is similar to Captain Gore and the Bandido Gang in that they are all antagonists in Disney Kingdoms comics who originate from unused scripts/attractions.