Optimus Prime, also known in Japan as Convoy, is a fictional character and the main protagonist of the Transformers franchise. Generally depicted as a brave and noble leader, Optimus Prime is the supreme commander of the Autobots in their fight against the Decepticons. The Transformers characters were developed for the American market after Hasbro representatives visited the 1983 Tokyo Toy Show. Some designs were modified and the coloring was changed; notably, Optimus Prime (released in 1982 as Diaclone No. 17 - Battle Convoy and in 1984 as Powered Convoy) was colored red, chrome, and dark blue. While the Diaclone version was intended to be a piloted mecha, the Transformers version was a sentient robot. The popularity of the Transformers toys resulted in comics, movies, and a TV series.

In the Transformers mythology, Optimus Prime is a Cybertronian, a member of an extraterrestrial species of sentient self-configuring modular robotic lifeforms (e.g., cars and other objects), a blend of biological evolution and technological engineering. He is the primary hero of the story, opposing the Decepticon leader Megatron.

Due to the popularity of the Transformers franchise, Optimus Prime has remained one of the franchise's most iconic characters, and one of the greatest and most recognizable fictional characters of all time. As an established pop culture icon, his voice has been portrayed by a variety of actors, with the most common being his first, Peter Cullen. Other actors include Garry Chalk, Neil Kaplan, David Kaye, Alan Tudyk, and Chris Hemsworth.

In the Transformers story, Optimus Prime, also known as Orion Pax, embodies strong moral values, exceptional leadership, and strategic prowess. Equipped with advanced weaponry and martial arts skills, he champions justice and peaceful coexistence with humans. As the bearer of the Matrix of Leadership, he leads the Autobots, engaged in an eternal conflict against the Decepticons. Originating from the ancient Dynasty of Primes, Optimus Prime's selfless sacrifice and rallying cry of "Till All are One" were pivotal in defeating Unicron. Reborn as Orion Pax, he embraced his new identity, only to reclaim his role as Optimus Prime to confront the Decepticons led by his former friend, Megatron, igniting the Great War on Cybertron. While his origins and persona may vary across different storylines, this depiction remains consistent throughout iterations of the Transformers universe.

The first-generation Optimus Prime transforms into a Freightliner FL86 cab over semi truck. Within his chest is a mystic talisman, known as the Autobot Matrix of Leadership or the "Creation Matrix", carried by all Autobot leaders. When Optimus transforms, his tractor cab disconnects to become a sentient robot, and his trailer opens to reveal an ion blaster, forming a combat deck. The combat deck supports a mobile battle- station and command headquarters armed with assorted artillery and beam weapons that fire automatically. The combat deck can also serve as a radio antenna for battlefield communications between the Autobots. The combat deck also included "Roller", a mobile scout buggy meant to scout behind enemy lines. When Roller is deployed, Optimus can see and hear what Roller sees and hears. Injury to one component is felt by each of the others. If the combat deck or Roller were to be destroyed, Prime could survive. However, despite the slight degree of autonomy they possess, the combat deck and Roller would not be able to survive without Optimus.

The original specification of the Generation 1 Optimus Prime specifies that Optimus Prime consists of three components: the humanoid "Brain Center" (which transforms into the truck cab), the "Combat Deck" (which transforms into the truck trailer), and the "Scout Car", a non-transforming six-wheeled buggy called Roller, which can ride inside the truck trailer. All three components can function independently, but injury to one is felt by the other two. However, in by far most of the fiction, the humanoid robot is itself Optimus Prime, with the other two components treated as mere accessories that disappear off the scene when Optimus Prime transforms from truck to robot mode.

Optimus Prime is the fictional protagonist of the Transformers: Robots in Disguise (Fire Convoy in the original Japanese version) branch of the Transformers universe. Based on the character of the same name, Prime once again leads the autobots against the Decepticons. His voice actor, Neil Kaplan, does his voice in a style reminiscent of that of Peter Cullen, the voice of the original Optimus Prime. Wired Magazine nominated Fire Convoy as one 12 most ridiculous Transformers ideas of all time.

Hidden on Earth as common, everyday vehicles, the Autobots are forced to emerge when Megatron and his Predacons arrive and wreak havoc in their attempts to attain the power of Earth's various energy sources. In this universe, Optimus Prime transforms into a fire engine. This is also the first incarnation of Optimus Prime to transform into a fire engine.^{[citation needed]}