Primacron

Primacron is ancient alien scientist from the G1 Transformers. He is the creator of Unicron & Tornedron. Despite that he is not purely evil, he can be considered as a villain due to his jerky tendencies of creating planet destroyers for galactic domination. He appeared in the episode "Calling of the Primitives".

G1 Transformers
Prior to the events of the series, Primacron's assistant created a group of Transformers called "Primitives". Primacron grew jealous of him & out of ambition, he created Unicron, who then rebelled against him by destroying his assistant, who later became The Oracle & injuring Primacron.

Millions of years later, Primacron returned for his conquest of the universe again. This time, he created Tornedron, a shapeless giant siphoning energy monster. He ordered the huge beast to drain energy from various planets alike & later on the Primitives who were assembled to defeat him. After successfully draining the Primitives, Tornedron left to return to its master. Unknown to it, Grimlock had secretly survived from being crushed by a drained Trypticon & secretly followed the energy drainer.

Upon Tornedron's return, it then turned against Primacron & tries to destroy him. Grimlock then breaks into Primacron's lab, seeing the latter is a small monkeyfishh-like alien. The Dinobot leader grabs Primacron & orders him to undo the damage he had cause but explains he tried everything but failed. Grimlock then finishes the job by throwing the reverse switch, undoing Tornedron's energy polarity, killing it in the process & restoring life on every part of the galaxy Tornedron went. To make such he doesn't do anything stupid again, Grimlock then celebrates by destroying Primacron's computer, much to the alien scientist's horror, while claiming it is the "smartest" thing he has ever done.

Trivia

 * Though not a medium, it may be possible Primacron could be the unseen "creators" in Transformers: Age of Extinction.