(Constitutional experts were surprised to discover that there is no law against undead heads-of-state. According to sages, it "just never came up".)
Atacres is over 400 years into his reign now, and his descendants -- the so-called "Rulers-in-Waiting" -- have had mixed opinions over the centuries. Revolutionary efforts have faltered because Atacres is, despite appearances, a fair and popular king, and trying to depose him based on his unfortunate... condition looks an awful lot like bigotry and prejudice, and everyone knows that a successful revolution these days is all about good optics.
That said, Atacres' relationship with his own state church is strained. The king is wary of clerics and paladins and will only grant audiences at a distance, or through intermediaries. One over-zealous -- pun intended -- holy man spaffing Turn Undead in the throne room, and all of Atacres II's hard work is up in smoke, or dust, or whatever the D on the Turn Undead table signifies.
The king's attitude to other undead creatures is complicated and evolving. He considers himself (un)living proof that not all undead creatures are soul-sucking monsters, but fears challenging his people's view of the walking dead. Rumours persist that he has held secret meetings with liches, vampires, and other high-functioning corpses.
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That image of Atacres popped into my head one day -- probably a weird after-effect of The Event™ -- and I thought he had potential, perhaps as an unusual NPC, the sort of thing a D&D party would go try to kill most days of the week. There's probably also a bit of an influence from Steven Erikson's "friendly" lich Bursting With Wit, from Blood Follows.
In terms of game statistics, Atacres is probably either some sort of lich with no magical powers, or a beefed up skeleton with the charisma and intelligence of your standard rpg wise king archetype.
