This infographic just about fits inside the Tardis. Just about. K9 and Kamelion are on this chart creators have done the right thing and counted them as Companions.
Got to say; this infographic reminds me of how much I disliked Visior Turlough when I watched the show as a young pre-blogger. I suspect I’d find the character far more interesting these days!
Adam Mitchell – remember him – is also included. He was the chap the 9th Doctor kicked out after just a few days. I think he wound up with some tech in his head.