And, not to beat a dead horse, aren't all character's in TiTs someone's OC?
If you consider characters in books and actual video games OCs of whoever developed them, I guess??? That's not really what the term is used for, though. OC generally refers to fan characters, 'sonas, and the like -- not characters created professionally for a given piece of media.
Excelia fits the common-use definition of an OC. Han Solo? Not really...