Xavius was once superhero The Summariser, but he's unfortunately been afflicted with serious desaturation. This has had the unpleasant effects of converting his previously awesome clothing to really stupid-looking robes, turning him a dark grey colour, and of inverting the colours of his speech bubbles. In addition, his superpowers as The Summariser appear to have been lost, perhaps forever.
- Xavius first made his appearance in The Thick Plottens, described by Gary Gygax as only "the evil". His actions appeared to match this description, as he was shown coercing The Wizard Of The Coast to create Fourth Edition.
- His next appearance strongly contrasted with those first impressions, as Xavius next appeared in Tower Of Dread, expending a great deal of magical energy to assist the protagonists.
- In Shadows Of Civilisation, Xavius actually met the protagonists, and tried to explain his identity. Unfortunately they did not take kindly to his appearance, and he was forced to tear open a plot hole to escape an ambush.
- In Fridge Logic, Xavius ends up in the Authorship Shrine. He meets the Author, and is dragged along for the ride when the Author takes off in the transportation module. Since then, Xavius has only appeared accompanied by the Author in the transportation module.