The Ace is someone who is ridiculously good at what they do (whatever that happens to be), and everyone knows it. People look up to him, envy him, are in awe of him. He has a reputation for doing the impossible, and may be Shrouded in Myth as people are unable to separate his real accomplishments from unfounded rumors. He will always live up to his reputation (if not exceed it), however -- if the man doesn't live up to the legend, then he's a Fake Ultimate Hero. In a work revolving around a specific activity (whether it's fighting a war, solving crimes, card games, or whatever), the Ace will be one of the best -- if not the best -- at it. In works lacking that sort of focus, they'll probably be extremely talented at everything.