Playing someone else in the game universe, of course... just like a pen & paper rpg. I find it really weird when people make themselves in rpgs! (that includes some of my friends) What's the point? Maybe people just want to see what they'd look like in the game engine, or feeling a bit too lazy to be creative in a game, but I've never been interested in that at all. The point of rpgs (imo) is to make characters and their stories. I also enjoy text roleplay and other forms of roleplay (did a lot of roleplaying on tegaki - no game rules, just plain rolepaying, with pictures, kind of like making a collaboration comic).
As an artist, I love creating characters, and I have over 150 original characters.That doesn't mean none of them have my characteristics... specially with RP characters cause in a roleplay you have to identify yourself with the character even if very remotely, just so you can put yourself in their shoes and be able to "think" like the character, and play that part... like an actor would do, I think.