Optimus Prime

You are Optimus, but you not a prime yet you are still a bot, but one day, you sacrifice your self to protect Sentinal prime, because Megatron is killing him, but unlucky, Megatron hit you with the gun and yo miss a hand. When you fall through the Cybertron, you saw all the prime and said "You sacrafice yourself for good, and here is the Creation Matrix, and you will be the next prime." You wake up and fly.