I have myself as creator but in the ownership tab i have the notation that character was created using in game assets from the game with a link to the official site and then all the images link back to the official site in the credits as well. You can also put the game site/company in as creator credits and add yourself as a designer.
Some of my OCs are player characters from video games that enable you to customize your characters, I use screenshots of the characters as references until I can draw my own references for them. My question is how should I handle the artist credits on the screenshots? The Character is mine, made within the game and I toke the screenshot, however, it's the game's assets most of the time. At the moment I've been crediting the game studio and linking to the buy page for the game or the studio's website. I don't know, however, if this is what staff wants us to do with the screenshot or what.
I usually just do the game dev company. But say if I was using wowhead to get fullbody out of game references I tend to credit wowhead.