When I was very young, all I knew about the background of the fictional character Flash Gordon was that he was a star polo player. I also thought he was supposed to be British, but I'm not sure where I got that idea. As it happens, very little about his background has been provided in any of the media in which he has appeared. For example:
The Newspaper Comic Strips: He was a star polo player and a Yale graduate.
The Movie Serials: He was a pilot and his father was a famous scientist.
The First Animated Series: Nothing I can recall.
The 1980 Movie: He was a quarterback for the New York Jets and had taken some flying lessons.
That's the entirety of his background as far as those sources are concerned. I'm not saying Flash Gordon needs more of a background (he's an action hero, after all), but I find it interesting how little we need to know about his life before Mongo. In terms of role-playing games, perhaps the lesson is that all you need for a character's background is a single sentence. The most compelling part of the character is that which emerges through play.