Looking for someone to play Orion, then eventually Optimus.

Born as Orion Pax, the robot eventually known as Optimus Prime would rise slowly but surely to fame–first as a law officer unafraid to stand up for justice, then as a great and powerful military leader who held the line against Megatron's Decepticons on Cybertron and across the galaxy. As the first legitimate Prime in many ages, heir to the Matrix of Leadership, Optimus Prime is revered by many and reviled by some, but always a powerful presence, in or out of battle.