Zorgo

 was a creature who had a long lasting grudge against the Doctor. He attempted to conquer time on 26 different occasions, but was stopped every time by the Doctor.

When the Twelfth Doctor and Clara landed on the Luminos Bridge on Myros, two robots greeted them and took a selfie with them — only for it to be sent directly to Zorgo, who identified him for his final plan to kill the Doctor. Zorgo then released a time dragon, which absorbed the time energy from the TARDIS, draining it into the dragon. The dragon then later blasted the two into Zorgo's lair, where he trapped them in a time bubble — however, despite the Doctor foiling his plans 26 times, the Doctor didn't remember who Zorgo was. After explaining his different schemes, he realised he was old and dying and couldn't remember why he was trying to kill the Doctor anyway and let him go. The time dragon then fizzed and grew large, spitting out vortex energy. One of these blasts hit Zorgo which caused him to become a baby again, and to be taken care by one of his robots. (COMIC: Zorgo the Terrible).