The Doctor

For anyone with basic knowledge of doctor who:

The Doctor is a 900-year-old Time Lord from the planet Gallifrey.
He has two hearts, and when his body gets worn out he can "regenerate" and change his appearance.
He travels through space and time in a machine called the Tardis (Time And Relative Dimension(s) In Space). He carries a sonic screwdriver, which can help him get out of ...sticky situations! Rose Marion Tyler was the longest companion to the doctor (of course). she didn't stay long tho the big bad wolf got her in the end(but she got what she wanted) .
But the Doctor never spends too long on his own, and always seems to find a friendly face or two during his adventures.