"Have you ever thought what's like to be wanderers in
the fourth dimension...have you? To be exiles?"

The First Doctor --
William Hartnell

William Hartnell's Doctor is probably the simplest. When he played the part the Doctor was an old man, exiled from his own alien race, who traveled in space and time with his granddaughter Susan. But, Hartnell gave the character a richness that another actor might not have. His Doctor wasn't completely loveable, but you liked and believed in him. Sometimes he stubbornly did what he wanted, regardless of the consequences, still you trusted him. Most importantly, though, you knew the Doctor was a good person. Which made you want to follow him into whatever adventure lay ahead.
Maybe he wasn't that simple.