Redcloak's failed characterization, and what it means for the comic as a whole.

[Bastian]

There's a succubus paladin statted on the WotC site.

On the other side of the coin, there are celestials in some splatbooks that have gained an evil alignment, yet are still celestials- they retain their Good subtype, and other subtypes like Angel.

Elder Evils has one, the servant of Sertruous, one of the Eldar Evils.

I commend your knowledge - the Succubus Paladin looks cool!