An undead knight, you know, a Spiral Knight from the Spiral Order, and he would have been corrupted by the zombies, spectres/phantoms and such, who would be taken in by the zombies, and all previous life in the Spiral Order would have been erased.
But what would he be called? And what powers of the undead would he have?

Idk. This is just an idea. A foundation (not to be confused with a fountain) idea. Perhaps he could have an army of zombies, like the Jelly King had jellycubes around him, and he could have totem powers, so if all the zombies died, he could rise them? It's a thought, but... i think it's a little too much like Jelly King, from what i'm writing here, but... it's just a suggestion.