Few heroes in any genre have the stature, nor command the reverence of Optimus Prime of Cybertron.
Earth’s greatest ally and protector against the Decepticon threat, Optimus was once a firm, fair and benevolent ruler on the Transformers Home World of Cybertron; as wise in times of peace as he was outwardly purposeful in times of war. It is only in private that this firm believer in the sanctity of all forms of sentient life would be clouded with doubt and a heavy spark/heart as to the lives lost in battle.
Not one to shy away from making the tough decisions, the very reason that the Decepticons and Autobots are even on the planet Earth is because of the decision the great Prime made to launch the Allspark into the vast reaches of space, out of reach of the rampaging and war-driven Megatron, his arch-nemesis who had ruled with him on Cybertron (before the latter Transformers’ hunger for power had been unveiled).
So committed was Prime to ensuring that the stated goal of the Decepticon leader, which was to take over the galaxy, never came to pass, that he jettisoned the Allspark, despite his realization that his planet would not survive long with its absence. Optimus sacrificed his war-torn home to save the universe; this capacity for sacrifice would become a theme of his very existence, as Prime is more than willing to lay down his own life to protect the lives of sentient beings.
In Transformers 3 Dark of the Moon, Optimus was one of the few Transformers who could understand the ancient Cybertronian language of monarchs that was microscopically-etched on the bifocals of Sam Witwicky’s (played by actor Shia Labeouf) glasses, inherited from his explorer grandfather, Archibald.
His ever-present nobility shining through, he was quick to befriend Sam and crew, garnering the young future-hero’s undying respect and loyalty; this would come become deeply important as Optimus, spent after what appeared to be the final battle with Megatron, urged Sam to push the all-powerful Allspark into his chest, where they would destroy each other and thus keep it forever out of Megatron’s hands. Sam, understanding the implications, chose instead to risk life and limb to push it into Megatron’s chest. It is a running theme that the gravity of Optimus Prime’s own willingness for self-sacrifice, often trickles down to those affiliated with him, which is the mark of a truly great and natural leader. Humanity should count itself lucky to have such a stalwart alien protector.