Since the Fallen was in charge of the universe's decay, I think Entropimus Prime has a nice ring to it.
this then: Thirteen original Transformers - Transformers Wiki. It uses "Vector Prime: In the Beginning" as source material. Remember, Prime is a title, not strictly a name suffix. Consider this for a real-world parallel, France was once ruled by King Louis XVI (Louis-Auguste de France). He is often refered to simply as "Louis XVI", but just because the prefix isn't always used doesn't mean he wasn't king.
i hate everyone and i just want to kill and shoot everyone in the face cuz i am supirior and look way cooler...prime