4. Adelaide Brooke
Bowie Base One Captain Adelaide Brooke (played by the wonderful Lindsay Duncan) was a pioneering hero of the future human race. She commanded the Doctors respect from her reputation alone and it increased as the threat of the Flood began to overwhelm the Mars missions crew. When teamed up with the Doctor they made a great partnership and she was a refreshing change to the more common wide-eyed companions. Her actions towards the end of The Waters of Mars were powerful and moving enough that it made the self-appointed Time Lord Victorious stop in his tracks and look at what he was becoming.