Leo Prime

Leo Prime, who has suddenly appeared on present-day Earth, is a Transformer Elder and he travelled from a dimension far away when he sensed the menace of Unicron. In his original world, he was a supreme commander known as "Great Lio Convoy".
He does not interfere with the battle between Optimus Prime and Megatron in order to prevent the confusion in time and space, but if Unicron awakes again he will wield his Ancient Sword to stop the force of evil.