It means original character, یا پرستار character. People create them for fantoms and such. I have a Hetalia one, Oregon, along with a bunch of people from our RP.
OC= Original Character I have a few, one of them that will probably never see that fanfiction world (I do not کریں شائع my Sopranos fics) is Sonia Moltisanti...the مزید level headed twin sister of mafia man Christopher Moltisanti. (TMI I know)