Gilgamesh was the heir to the throne of the ancient city of Uruk. In his childish naivety, he did not understand the concept of "death", he thought that the king should be spared from it. As he grew, his fear of death became a ongoing phobia. An alien ship crashed near the city, and he met the alien inside it: Utnapishtim. He was from a race that had achieved immortality, and he gave to him using his alien machines. Thus, the king Gilgamesh never ages and is impossible to kill. But, as generations passed, Uruk declined: all people were sad because their king's immortality reminded them of their own mortality. So, he staged his death and left the city, which became active again.
Gilgamesh became an errant, and saw all the historical civilization, many historical peoples, took part in several historical events. The single thing he despises the most is war, but he is unable to do anything to prevent any of them.
Finally, a nuclear reactor explodes, and all humanity perishes. All, except for Gilgamesh of course. But he saw a chance: a project in the United States to take frozen humans to other planets. Gilgamesh completed the plan, and explored the universe to find a new planet to let humanity start again. He met other alien races, and eventually settles at another planet. The embryos become a tribe and, centuries later, a technologically advanced society. This new human race, unaware of being alien to that planet, organizes a space journey to planet earth, after discovering life in it. Gilgamesh joins it, but the tripulation dies during an accident after arriving. Gilgamesh is then left alone on a devastated planet.
He eventually meets other aliens that preserved human life in a similar manner, and would restore the human race when radiation had lowered to allow life again. Another alien race establishes itself on earth, but is followed by an enemy ship and destroyed. Gilgamesh kills the single attacking alien, but realises that the action was observed by others of his race. Fearing a counter-attack that would devastate the small tribe of humans, he takes the spaceship in an attempt to take the fight to the space. He meets an alien outpost on Mars, of the same race as those who made him immortal, and together they destroy the whole attacking fleet.
Gilgamesh is then sent to another level of existence, similar to Olympus, where he meets other immortals, with him being the only one who was mortal once. He is proposed to move to yet another higher level of existence, but requests instead to live his life again.
Gilgamesh the Immortal contains examples of:
- Ancient Astronauts: The Epic of Gilgamesh explained with aliens.
- And I Must Scream: Go ahead, immortal, scream until you break your lungs. It will do you no good: the nuclear reactor exploded, and humanity perished.
- And There Was Much Rejoicing: In Uruk, when they thought that Gilgamesh had died.
- Been There, Shaped History: Subverted. Gilgamesh could not prevent World War II or the Holocaust... nor the bombings of Hiroshima and Nagasaki, the conquest of America, the crucifixion of Jesus, the fall of Rome, the defeat of Napoleon, the assassination of Julius Caesar, and so on... he has been inside all of them, but he could never change history.
- Complete Immortality: He does not age, and nothing can destroy him. Not a Sumerian blade, not an atomic explosion of hundreds of megatons (yes, he's been in the core of such an explosion... and more than once!)
- Creator Provincialism: Averted. Sure, Argentina as a country didn't exist in the time of Uruk, but with a character that spans from ancient times to the end of the world and beyond, they could made an episode taking place in Argentina (any time from Napoleon to the end of the world would do). But no, not a single mention of Argentina in this Argentine comic. The closer he ever got was to Peru during the colonization of the Inca empire, and crossing the Atlantic ocean from Africa to Brazil.
- The Faceless: When he was serving as a Roman legionary, Gilgamesh heard about a man from a distant province of the Empire who was preaching revolutionary ideas: love between all people, a single god, that all men are created equal, even the slaves... so Gilgamesh headed to meet him. But he did not arrive at a good moment: the man was being judged, accused of wanting to be a king (we never see his face, just in shadows, and never hear his name). The Roman governor saw no real crime, but the people insisted, so he showed a vicious criminal. He proposed to pardon one of them. Gilgamesh was horrified by the answer of the mob, which echoed in his mind for all eternity: "Give us Barabbas". The prisoner was sentenced to crucifixion, forced to carry the heavy cross and wear a crown of spikes. The skies turned red, and he died. And Gilgamesh could not do anything but watch. It goes without saying who was this man, not shown and not mentioned, right?
- From Bad to Worse: Gilgamesh became an immortal king, capable to spend generations taking Uruk to the greatest glory... but people hated him. He thought that a common Empire may unite all the world and end wars... but it always ended in a bloodbath. He thought that the benevolent aliens may help to reduce human violence... and an army of barbarians crushed the aliens. He thought that Jesus may lead a social change... and you all know what has happened to him. He thought that Napoleon would finally end monarchism... and he became a conquering emperor. He thought that human development would make a change towards peace... but it was only a development in finer and greater ways to wage war. And, finally, humanity itself perishes, and he remains the single living thing in a dead world.
- Hope Spot: Several times Gilgamesh thinks he has found a way to finally see humanity live in peace and prosper... and each time the hope is utterly destroyed in the end.
- Human Aliens: Averted. Utnapishtim and his race, the "Martians" (but not from Mars), are Little Green Men. Each other alien is basically one Eldritch Abomination even more horrific than the last.
- Last of His Kind: Humanity died, all the world is a dead asteroid, not even the cockroaches survived... but Gilgamesh is still roaming the empty streets.
- Our Vampires Are Different: Gilgamesh met vampires once. They were creatures who lived underground, fed with minerals, and had to escape to the surface, where they could not eat common food nor find those minerals, except in human blood. And that's where fantasy ends. No flight, no turning into bats, no invulnerability, no fear of crosses... they can be killed just like any other human.
- Society of Immortals: The race of the Martians, who built an Immortality Inducer that makes them immortal.
- Who Wants to Live Forever?: Deconstructed. Since the middle ages, Gilgamesh became completely exhausted of life and the human obsession with war. And being unable to do anything about it just makes things worse.
- You Can't Go Home Again: Roaming in the desert during the modern age, Gilgamesh returned to Uruk. For a moment, he closed his eyes and heard the merchants, the priests, the warriors, the people building the wall... but only for a moment. The scream of a hyena broke the nostalgia, and he saw Uruk as it really is: just some rocks, some pieces of tools... and the sand, the wind, nothing remains of the proud Uruk.
- You Shall Not Pass!: Gilgamesh vs. a complete army, over a frail bridge crossing the pit of an active volcano. Needless to say, the bridge broke with the weight of so many people, and they all fell into the lava and died. Of course, all except Gilgamesh, who took some days to get out (lava is a bit sticky, it's not water).