Optimus Prime

"One Shal Stand, One Shall Fall." - Optimus to Megatron.

Optimus Prime (voiced by Peter Cullen) is the Leader of The Autobots, & one of many transformers that live on the planet of Cybertron. He is Megatron's arch enemy, however the two were once great friends. Before the Great Cybertronian War, Optimus Prime was known as, Orion Pax, a member of the Autobot Elite Guard, inspired by Thunderbolt, after he joins, he's given a mission to stop, Straxxus, the original Decepticon Leader. During the battle Orion is seriously injured, but still functions, gains the Matrix of Leadership from one of the High Council members, is reformatted into becoming known as Optimus Prime, & with the other transfomrers at his side, he finally defeated Straxxus. He is strong, wise, brave, & caring for his fellow friends.

After Straxxus
After the battle with Straxxus, Optimus took command as leader, & orgistrated many operations to explore the galaxy. Then everything when Megatron appeared, he then declared war on Cybertron, separating those that his friends into becoming his enemies, including his brother, Maxion, reformatting him into becoming Scourge. The war has spread to the United Universe as Optimus, & his Autobot allies continue to fight The Decepticons.

Trivia

 * Optimus is one of the only Autobots that actually cares for life, organic, & inorganic.