Every system of transportation has a sort of avatar, an eternal nomad, someone who has been bound to it in an integral fashion, never able to stop moving. There is, naturally enough, the Flying Dutchman, who cannot walk past sight of the sea, and the Wandering Jew, who has not slept in all the tens of thousands of years that he has lived. Both, of course, became what they are long before there were any Dutchmen or Jews to speak of.
But there are more wanderers than these. Amelia Earhart, for one, who went on her last recorded flight and now spends all her immortal life in airplanes, sometimes the pilot and other times a passenger, and whose rare moments on the ground are spent in transit between planes. It's been generations since she's walked outside an airport.
There's a crazy long-haired German who sleeps on the subways, too. How he manages to move between them is unknown, but he's been seen in every subway in the world. To those that know of him he is the supreme transporter. He can get anything that you desire to any place in the world, so long as you can make it worth his while.
The Busman, perhaps the last passenger on Blaise Pascal's abortive public carriage line of 1662, is a figure found exclusively in the Old World, lacking the German's ability to skip between circuits of his mode of transportation. He has ridden passenger, driven the largest articulated buses, and even hijacked his fair share over the years. The Busman is given over to mercurial moods, perhaps the least psychologically-adapted to his immortal existence. To one he is jovial, even benevolent, and to another... Well, he has hijacked his fair share of buses over the years.
Perhaps what these nomads (and those that know of them) look forward to with the most curiosity is the advent of space travel. Who will be the next to join their ranks, and when? Or have they already a new companion, who knows not that he has peers in his new life?