I will take the opportunity to update mine.
Oberon: Jenna's in Project X. He was a right bastard when he had his King hat on. But there was Oberon, the King, and then there was Oberon, Antonia's grandfather. Fortunately, he died before he could start plotting uses for Antonia beyond her stint in the Rowan Vert.
Finndo: Never really interacted with a Finndo. Still. But Al's guest appearance as Angry!Finndo in a previous incarnation of Blackmoor was awesome.
Osric: Alan Mulroy's. Eye of Harmony. I still haven't seen a better one.
Benedict: Shannon's in the long dead Too Long in Exile, Rich's in Endless Struggle, and Brian's PC in Exodus. Rich's characterization of Benedict was the most psychologically complex portrayal I had ever seen until Brian started playing the mentally damaged Benedict in my game. Shannon's managed to both be intriguing and infuriating at the same time and drove my character nuts. Arref's in Grand Affair is universally applauded as the man you knew you should stay away from, and yet couldn't seem to stay away.
Eric: Rich Ditullio's. The Endless Struggle. Brian's in All Our Yesterdays. Fabien's in The Fire's of Greymoor.
Corwin: Larry's in Winds of Change. He was everything I expect from Corwin; a lying, arrogant, swaggering man with delusions of godhood and an inflated sense of entitlement. Lord, but Janelle disliked her father.
Deirdre: I don't really interact often with Deirdre, oddly enough. But Jenna's in PX was inspiring for my character for none of the usual reasons. Paul's in Strange Bedfellows is interesting, though I've only had the one scene with her so far.
Caine: Dana Bayer's. Best Intentions. Sneaky bastard. Jenna's was also a lot of fun to play with in Project X, and Rochelle knows there is no one better to get up to no good with in Ray's Portraits of the Past then Uncle Caine.
Gerard: Frankly, I've never really seen a badly played Gerard. But I have to say Dana's in BI fits in with my idea of Gerard pretty well. Project X's Gerard was pretty neat too. He was an excellent Uncle/Brother in Law.
Julian: Jenna's and Juli Halbur-Herrera's in King of May are still the best. Though Brian's interpretation of him as a PC in Tears from the Sun is just wonderful.
Fiona: Fi's tough. Alan in Eye of Harmony and Shannon in TLiE both did a great job on her. But Jenna's was one sly little bitch in Project X. I never interacted with her, but I got to see other people do so, and heard the behind-the-scenes workings of her mind from the GM.
Bleys: David Miessler-Kubanek's in SW. I could take him home to meet mother, but he'd probably hit on her. Mel's in Time Under Chaos is worth noting as well.
Brand: Juli Halbur-Herrera's in Time Heals All Wounds and Alan's in EoH and Age of Reason.
Llewella: Dana's in BI, and Shannon's in TLiE remain the gold standard for me.
Flora: David Miessler-Kubanek's in Shadow Wars. Yorlum's in Successors. She was brilliantly funny as Portia's mother. Polemarch's in A Divergent Path is both the perfect foil for *Portia's ire, and a sly little player.
Random: Patrick Sander's in Unholy Alliances. Logrustendril's in Two Thrones.
Mandor: Mel, Mel, Mel! Time Under Chaos. The very best Mandor I have had the pleasure of watching and playing with, and being turned into a cat by.
Merlin. Actually, I have to say Time Under Chaos' Merlin is working well for me. Assuming that is Merlin....
Swayville. Yorlum's in Age of Reason. He takes that Exalted Shapeshifting thing to a whole new level.
The Unicorn. Rach's in Light from Shadows.
To my non Zelazny list:
George: Rich's from ES
Torcal. Dana's from Best Intentions. He makes my skin crawl. Then there's Jolyon the forest ape, the horses of Kiara, Juliette and Julian, and of course, Juliette...and Fleur. OK, I really like all of Kiara's circle of NPCs. Don't let it go to your head, Dana
Castle Guards: Jvstin. Strange Bedfellows. I like that all the ones I've come into contact with had separate and distinct personalities. Also, Poul. He's an awesome Page.
Kovikin & Kal'El. Shannon's from TLiE (though I have swiped Kovikin and gave him a completely different personality for Exodus)
Megan. Yorlum. EoH, Successors. She's a part of Age of Reason, but I haven't seen her. Al's also really good at officious clerks. You just want to reach out and strangle them all with their pocket watch chains.
Kieran, Robert, Persephone, Tytus. Craig's Tears from the Sun. Persephone and Tytus are exactly
typical teenagers. Granted, they're teenagers with sorcery, but still. Kieran is a charming and gallant fellow.
Shadow Stepper, Tornado & Fiach: Jenna, Project X. No one writes horses as well as Jenna. She knows the subject matter very well, and it shows. But the personalities she gave these magically enhanced horses were absolutely perfect.
*I will play Portia in a game that goes through completion one day, darn it!