This should be fun.

Just like the RPGnet version, minus the rules.

Traveller
Origin: A mysterious human-looking being claiming to hail from a distant off-world human colony in the far future.
Powers: The Traveller is a highly educated scientist and inventor, with access to vastly advanced technology. He usually prefers parlay to combat (to which he's not particularly well suited, save with extensive preparation).
As a hero: Returned to our time and planet to prevent the downfall of mankind's vast stellar empire, due to something called "The Virus", and may recruit or join the PCs' team.
As a villain: A greedy and ruthless trader who's travelled through time and space to bleed our planet dry of everything it has to offer; natural resources, works of art, even people (sold off as slaves or pets to strange alien races), you name it.