Sopitas said:
Weren't Angel and May Lee also created by Eolith?
May Lee was. K9999 and her were the only characters created by Eolith. Angel was based in a rejected character design SNK had. Igniz was a non-fighting character from NESTS (like Misty), that Eolith decided to make the last boss (SNK originally had planned for the old man, Master NESTS, to be the boss of KOF2001). Original Zero was implied to exist in KOF2000 (since we knew that the Zero from that game was a fake), and Foxy had already showed up in KOF2000 as a striker.
And even if May Lee and K9999 were created by Eolith, I'm pretty sure SNK has the rights to use them. May Lee has already showed up in Kim's ending in SVC: Chaos. And, sincerely, I don't think SNK would be stupid enough to let Eolith create characters for KOF that they can't ever use again... although I'm also pretty positive they don't plan to use neither of them ever again (specially K9999).