If you do start watching Doctor Who, WATCH IT IN ORDER. No, I don't mean that you have to start with the shows in the 60s, and nor do I mean that you need to watch NewWho in order... But within each season, watch the episodes in order. The stories build off each other, so unless you want to be COMPLETELY confused, you need to watch the episodes within each series in order.
The Doctor is an alien with a phonebox time-machine which is bigger on the inside.
He's 900 something years old, and travels around time and space, adventuring with various companions. He has a way of cheating death- he regenerates, changing every atom and cell in his body. Weird, huh? Still, it's ingenious, because it is what has allowed the show to go on for so long, with different actors. Currently, there are 11 regenerations. 11th doctor is my favorite.
He's the one in all if not most of my graphics.