A Couple Villains

A dragon that runs a thieves' guild. Its lair is at the bottom of a huge conical, spiralling pit. Each level has a different theme: carnival, torture dungeon, underwater ruins, knightly castle, thieves' guild classic, fire & puzzles, Oops! All Illusions!, shrinking & expanding gravity warping teleporting nonsense, and at the very bottom a cavernous hoard room with the dragon crammed into it. Maybe the hoard room is extraplanar?

Just a horny summoner. All he wanted was a harem full of succubus waifus, and now the succubi have charmed him and are using him to summon more and more fiends, slowly corrupting the foundations of the city and arranging for some dark rituals to take place.