Leo Jaeger (imposter)
Talk about it here.
A man who looked similar to Premier Leo Jaeger became the stand-in for him when he had surgery that left him with a scarred face. As time went on, he gained more and more power as people started to forget that he was a replacement.
Wishing to cling on to power as the leader of Colony 34, he postponed the election for five years. He sanctioned emergency powers that prohibited unsanctioned gatherings but later allowed the election.
However, he was trying to persuade the populace that there wasn't a fuel crisis. He was later re-elected by the populace and wanted to execute Ace but the Seventh Doctor managed to stop it. After being revealed by the Doctor, Ace and Hex, that he had people executed to use as fuel, even murdering children, he was attacked by a mob. (AUDIO: LIVE 34)