Doctor Who: 10 One Off Monsters Who Should Return (And The Stories They Need)
3. The Celestial Toymaker
The Celestial Toymaker is an extremely powerful being almost as old as the universe who placed people into childish games in order to try and win back their freedom (though he often would simply kill those who defeated him, the sore loser that he is). The Doctor mentions in Amy's Choice that not having a physical form can get some more conceptual enemies down after a while and thats exactly what the Toymaker does. Grabbing real people to entertain him in imaginary games.
The Doctor can be ensnared again and forced to play out his games, even more deadly seeing as he has defeated the Toymaker before in the William Hartnell era but this time the Doctor can fight back through forming an uneasy alliance with the Dream Lord, an aspect of himself he must let out when placed into the Toymakers imaginary world. The Dream Lord is the Doctors only chance of having someone who can also manipulate the reality around them and help the Doctor return to reality. Though the Dream Lord hardly wants that, seeing as it would mean he would stop existing again. Therein lay the makings a reality-bending, character building triumph of an episode.