Are you looking for spell use, stats, feats? a complete NPC?
Have a look at the Rogues Gallery forum, it might have what you want or give you a start.
What books are you limiting yourself to?
I'm not going to provide many stats/feats/combos (others can do much better) so I'll ask some Q's to get you thinking:
Some ideas and thoughts.
Undead the king has created that are loyal only to him. As many as he can create/control. Use feats that boost the amount and or power of undead
As many golems that the kingdom/king can afford, commanded only by the king.
Any summoned/called/allied outsiders? what about fanatical followers? (And on that note, who will NOT rush to the king's aid??)
Undead, golems parked throughout the king's personal chambers to protect him from intuders.
One thing that is often overlooked (maybe on purpose) is that the kning will have the best of EVERYTHING he can get and not just a $$ amount based on level. So even at ninth level he could have weapons and armour of +10 equivelent (he is evil, so potentially he doesn't trust anybody). The best WIS boosting item, protection items for everything and worn everywhere including up the wazoo.

Unless the party take the king out without alerting anyone, they will likely not have time to take more than anything easily grabable before needing to run.
Other than being an evil king, any themes that you want to follow? Who is the king's deity (or conept) and what domains does he have?