3. Tim Latimer (Human Nature/Family of Blood)
Tim Latimer is probably one of the most interesting human characters that we come across, but his uniqueness seems to get completely overlooked in the resolution of the story. Exactly how psychic is this kid? How can he communicate with the fob watch? He seemed to have an immediate bond with the Doctor and Martha, even before they reveal who they are. Tim is brave, inquisitive, and selfless. I loved what he brought to the table in Human Blood, and really wished he would have hopped aboard at the end of the two-parter. Admittedly, I'm a sucker for a historical companion, but I would have loved to see a clairvoyant boy from 1913 travelling in the TARDIS. Finally, a teenage companion I can get behind.