6. Kamelion Resurfaces
Kamelion was an interesting companion that should be revisited. The technology exists now that he could be done as a CGI effect or an updated outfit. Better yet, cast an actor in the role and have them appear human during the series, only revealing their robotic nature periodically. During the classic series, the robotic character was operated behind the scenes by a single engineer. Once that man died, there wasn't anyone else who could operate it and he wasn't used again in the series. The Doctor always seemed to have an affinity for alien companions, whether Romana, Turlough, K-9 or even Nyssa. The shape-shifting android has unlimited potential as a returning companion or an antagonist, since he was once a pawn of the Master. Without the Doctor's influence, he could have easily gone bad or fallen under the control of another villain.