2. Sontarans
In my opinion, the Sontarans werent brought back to their full potential. They were the stars of several episodes in the Classic series but in the reboot? Theyve been in one double episode. Of course, this isnt including Strax: the Sontaran who turned good. Although Straxs story is interesting, hes not the cloned war-machine that is expected of a Sontaran soldier and therefore, he isnt really a threat or much of a monster, apart from that brief moment when he forgot his friends. How could they be brought back? Any type of fast or slow invasion would make for a good episode. There could be just one Sontaran, left, presumed dead, who then rises up and starts a Sontaran empire anew, anything could happen! And now, with the Doctors companions as they are, there could be a twist Strax. How would he react when going into battle on the Doctors side
against his own race. Would he stay true to the Doctor and his friends, still repaying his debt? Or would he re-join forces with the Sontarans and destroy those that he had once held so dear?