BBEGs with really bad sounding nicknames from the PCs...

[Rel]

I'm going to dissent. That's a childish reaction.

I guess I'm an "eye for an eye" kind of guy.

 

[Kyrail]

Currain, a minor player in the grand scheme of things, but still a menacing figure who almost destroyed an entire community of 2,000 people, and killed 2 PCs... he wore a skull mask and was henceforth "Skelator"

 

[Mr. Kaze]

Elemental Evil Substitutions...

In my experience, players typically replace strange and obscure names with derisive alternatives simply so they can communicate about this NPC or place without having to remember what you called it. To this end, I tried to give my NPCs that I expected the PCs to pave-on-sight names that were similar to actual names, but memorable enough due to their presence in common culture. Need a Merovingian-style character? We call him "Merlot Vaughnagan". An evil shaman is "Dearth Voodoo-er" and his grizzly bear is "Animalkin Skywalker". They have a long-standing feud with the half-demon, half-green-dragon "Oni Con Wasabi". "Oret the Cull" is a diviner that has a history of sacrificing live creatures to read their entrails. The "Sporedmaster" was a Myconid/Troglodyte hybrid. A cross dresser who called himself "Tessimon" was derided by other NPCs as "Tass the Man". There were a few others, but they all beat trying to pronounce "Mereclar" only to have the players re-brand him "Mary-Claire".

I've also seen the more traditional "Hedrack" be permutated into "Hat Rack", and -- while not even remotely a BBEG -- "Meepo" being regarded as "Meatball".

 

[Emperor Valerian]

On the other hand, it would have been really neat to say something like "OK, <insert name of character> has been shredded to death by Mr. Happy's devastating attack..."

"I'm sorry... but your character was decapitated, bisected, and sliced into tiny salad serving cubes by Mr. Happy. Have a nice day!"

Oh, I am so twisted...