The details between these events differ between universes. Sometimes Optimus Prime merged with Vector Sigma soon after defeating the Hate Plague, and returned much, much later as Star Convoy. Sometimes Optimus Prime partnered up with Marissa Faireborn to receive upgrades through mutual kissing. Sometimes... look, he did a lot of weird stuff, okay? He later sacrifices himself to restore the Matrix of Leadership.
Megatron came upon Optimus and challenged his old foe to a duel. Optimus managed to gain the upper hand, but hesitated to deliver the killing blow when he discovered that Megatron had married the Matrix to his spark, corrupting it. Several Decepticons then swarmed Optimus, allowing Megatron to blast a hole through his chest. Dead and defeated, Optimus plummeted down into the bowels of Cybertron. Pax Megatronus Rodimus and Duke travelled far beneath Cybertron, where they discovered Ultra Magnus- the Autobot god of death -carrying Optimus's body away. Earth: R.I.P.
In the United Kingdom, this Optimus Prime was released as an Argos exclusive along with several other sets branded as part of the Reveal the Shield subline imprint. His United States release was initially claimed to be exclusive to Target by online retailers from Asia, but even though the other Reveal the Shield products eventually became available at Target, Voyager Class Optimus Prime was released as a Toys"R"Us exclusive in the United States instead, complete with a "Toys"R"Us exclusive" sticker. Also, both his United States and Asian releases lack the "Reveal the Shield" logo the United Kingdom release has (but still feature the "Reveal hidden images" call-out).
Optimus Prime is usually depicted as being a member of an ancient Transformers race called the Dynasty of Primes, often receiving the title "The Last Prime" in many stories, in which he is depicted as being the last of the Primes. In the Transformers: Covenant of Primus, it was established that Optimus Prime was the last born of the original Thirteen Transformers. It was his unique spark and his inspiring reassurance that "All are One" that allowed the Primes to rally and succeed in their battle against the Chaos Bringer Unicron. When tragedy at last ended the era of the Primes and brought forth the new race of lesser descendant Transformers he alone chose to be reborn in the Well of All Sparks as one of them, that he might know them and their needs more completely. All memory of his past life gone, he took the name "Orion Pax" and sought his way like any other robot on the new world becoming Optimus Prime once more when receiving the Matrix of Leadership when Cybertron faced a new enemy in his former friend, Megatron and his army of followers, the Decepticons. This brings a Great War to their planet of Cybertron. Optimus's origins and personality can vary depending on which "universe" he's seen in. This origin is the most consistent between the various incarnations. Further differences are listed in the respective sections below.
Of course, many voice actors have voiced him in different TV shows and video games over the years, in both English and Japanese. Most notably by a Power Rangers actor and a Batman voice actor. The latter is Will Friedle, who voiced Bee in the most recent series, Robots in Disguise, plus cameos in Rescue Bots, Transformers Prime, and the Predacons Rising TV movie. Friedle is well known as Batman’s voice in Batman Beyond. As for the Power Ranger, that would be Johnny Yong Bosch, who played Adam Park, the original Black Ranger. Bosch was Bumblebee’s voice in the video game Transformers: War for Cybertron.
If Optimus ordered his troops to come to the humans’ aid, they found themselves taking part in a struggle in futility, as the entire town was near-weightless, meaning they couldn’t put the humans anywhere where they wouldn’t float away once more. Then, the Autobots heard Decepticons approaching. Helpless in their current position, the Autobots were quickly eradicated by the Decepticons.