Rose Tyler :Defender of the Earth
I'm currently on series 5 of Doctor Who and I am already missing David Tennant. My favorite companion the Doctor has had would be Rose. They really grew close together and you could just tell how much they love each other during Doomsday. I literally cried during that episode and I just love them together. Oh I'm crying now so I got to go. :'( They're just so perfect together.