Though I'm sure he was totally non-canonical as I played him (all I've read are the few references to him in the core books), Kas.
I mucked with the D&DG templates a little, basically to reduce the bennies for hero-deities. Kept him human (as in, non-outsider), made up some back-story that I liked.
The PCs were never exactly intended to run into him, but because he was on the PMP and in the area where the PCs were adventuring (and, indeed, tied to the plot-line they were investigating), I decided to put him together, Just In Case. Mainly I saw it as an exercise in using D&DG's mechanics.
Lo and behold, the PCs do run into him -- and they're all around 5th level. They go to interrogate him (he's leading an army of kobolds through the woods, which makes sense in plotline, and they figure "if he's working with kobolds, he can't be that tough!"), the Cleric of Corellon manages to Bluff himself off (yes, successfully), as "Voorhas the Ranger, keeper of these woods!" and demands to know his business.
A rough exchange of dialogue, and Kas issues a warning-threat ("let us along our way or die," or something of the sort.)
Cleric casts Hold Person on Kas. I had made the decision not to change his type to Outsider (based on Vecna being Undead), so he's not immune. Critical fumble. Kas is held.
The Barbarian makes a coup de grace attempt when they realize his (obviously subserviant) companion is whupping on him. Kas has a huge Fort save, naturally, but it's not infinite. I do the math -- he needs an 18 or higher to survive. 19. Dodged the bullet of trying to decide whether or not to fudge the roll.
At this point the party realizes they're in over their heads, and run off...
Much later... Players enter a tavern -- shortly they after, they hear a bellow from across the room. "VOORHAS!"
Yes, Kas is drunk, and happy to see anyone he knows in this world. You see, the guy who summoned him was a staunch Vecnite, and betrayed him at the first opportunity. The characters notice the bandaged stump. And no hard feelings about the attack -- he's not going to contest a man's right to protect "his woods."
Kas, fresh from the Nine Hells, has no money, and few material positions -- so he's perfectly willing to let the players hire him to act as their bodyguard. And he acts as one, for a while, until they go to check out an orc encampment in some old tombs. Intimidated, the players send Kas to investigate -- after he's been gone a lengthy while, the Rogue goes (while invisible) in to check out the situation, only to find the deity slugging down ale and swapping war stories with the orcish general.
Deciding he's more trouble than it's worth, the players decide to leave him behind.
Which was fun to play out as a storyline, but it's harder to express the more enjoyable part -- playing out the personality of this rugged, ancient, drunken general. "I'll tell ya, it's nice being able to just sit here and drink and relax and drink with ya, after being stuck in the damn INFERNAL PLANES for SIX HUNDRED FRICKIN YEARS. Y'd think you might find a cuppa mead there, y'know, but no, not mead, just trenches, trenches you dig for SIX HUNDRED FRICKIN YEARS."