Mega Man X8 (Rockman X8 in Japan) is the tenth and seemingly final installment in the Mega Man X series, released for the PlayStation 2 in 2004. The game was later ported to the PC in South Korea and Europe, and was the only game in the series not to be available in Japan first.
- Mega Man X
- Optic Sunflower
- Cut Man - (Secret Boss)
- Layer - a scantily-clad Navigator with a calm and cool demeanor introduced in this game. She's in love with Zero, but he is apparently oblivious to this. Her expertise is in boss strategy, and can give the player hints on how to defeat them.
- Pallette - another Navigator introduced in this game. She is young, knows about a stage's secret capsules, and rare metal locations. She also runs things in the R&D lab by making items for X, Zero and Axl out of Metals.
- Bulbrite (Q in Japan) - a small flying Mechaniloid enemy commonly encountered in the game which bonds or attaches itself to others of its kind to become a greater threat.
- Avalanche Yeti - Known as the "Guardian of the Eternally Frozen Fields", Avalanche Yeti was placed in charge of managing the South Pole Environment Center (Central White) despite his inexperience. Settling into the position, he became troubled by the ever-worsening environment. Eventually, Avalanche Yeti went Maverick due to his copy chip embedded with Sigma's data. Yeti spoke with a deep Russian accent and when confronted by Zero, Yeti tells him, "If you will not see our point of view, at least let us be." This indicates he didn't wish for conflict.
- Bamboo Pandamonium - He and some of his Mavericks are after the rocket center in Booster Forest. His main attacks consist of his Green Spinner missiles, and occasional drills from the ground. But in Overdrive, he will try to lunge at the player, and this is instant death if it connects. He'll also in Overdrive Mode sends out a rapid barrage of missiles, some coming from above.
- Burn Rooster - was a reploid that thrived in hot conditions, being extremely resistant to heat. Working in the Industrial Waste Facility in a volcano, he utilized the natural heat to burn waste. However, he soon became sick of it, and his anger allowed the Sigma Virus in his new-generation chip to take hold. He accuses the Hunters of being no better than the Mavericks they had destroyed, saying "Is this your idea of justice?! Killing those who don't follow your ideals?! It's you who are wrong!"
- Dark Mantis - in charge of security at an underground army logistics base (known as Pitch Black). His abilities allowed him to function in complete darkness. After turning Maverick, he seized control of the defense mechanisms in the base, making travel in the area for Maverick Hunters very difficult. His accent was a Texan cowboy drawl, deep and measured, which fit his look and personality.
- Earthrock Trilobyte - was a technological worker in charge of overseeing the crucial duty of mining Rare Metals needed for outer-space development. When his data turned Maverick, he took control of the area until he was stopped by the Maverick Hunters.
- Gravity Antonion - His AI intelligence systems were given an immense boost at the time of his creation. This enabled him to be the head researcher at the anti-gravity lab (Primrose). When he went Maverick, he presumably masterminded the death of his colleagues and attempted to use the research equipment to destroy the hunters.
- Gigabolt Man-O-War - worked the menial task of supplying energy to the above-water city (Dynasty), moving from area to area. When his new generation chip went Maverick, he went on a rampage, stealing energy for himself and causing destruction until the Hunters defeated him. On a side note, the virus damaged Man-O-War's systems so badly that he says random things during battle, such as "muffin", "marzipan", "cheese and fries", and "potato salad".
- Lumine - Leader of the new-generation Reploids and director of the Jakob space elevator, Lumine is a new generation-type Reploid like Axl, but far more advanced and the real antagonist of the game. Part of the New-Generation Reploid model line, he is the penultimate version with very powerful shape-changing abilities and the power to copy Reploids' most powerful attacks. He is kidnapped by Vile in the initial mission and is unseen (though often referenced) until the later stages of the game, when he steps out from the shadows and reveals his intent to rule in Sigma's place. When defeated, he explains that the New-Generation Reploids can go Maverick at will because of Sigma's data, and that it is not an infection but a choice.
It is the year 21XX. The Reploid rebellions across the past years continue, seemingly with no possible solution despite the Maverick Hunters' best efforts.
Seeing this as a completely unnecessary worry, mankind has begun the next generation of research and development by constructing an orbital elevator able to take equipment and handwork to the moon where they seek to expand their horizons to space. This operation is labeled as "Jakob Project", with the orbital elevator bearing its name.
As another part of the project, a highly advanced new generation of Reploids is dispatched to the moon surface in order to work on the plans of the project. Everything seems to be running smoothly until one of the personnel transport carts explodes off the spiral track of the elevator and crashes down near the elevator site.
X, who was tracking around the area, is the first to arrive. After requesting a rescue squad, a rising figure from the debris draws his attention. As the many bog bodies come out of the fire, X's face changes into one of deep shock and fear. A vision of a nightmare appears in front of his very own eyes: an army of Sigmas climbing out of the crimson fire.
A single young Reploid who was being protected by the Sigmas is revealed, as he explains the situation. The Sigmas within the transport are really some of the New Generation Reploids, able to use DNA data to change their shapes. They are the perfect workers because they can change their shape according to a task. Claiming that their new systems makes them immune to all viruses, X relaxes as he asks the identity of the young Reploid. He introduces himself as Lumine, the director in charge of the Orbital Elevator, and the Jakob Project itself.
A few hours after the crash, a Maverick riot near the elevator site in the Galapagos calls for X, Axl, and Zero in order to stop a unique crab-like Mechaniloid. They manage to defeat it, but are then interrupted by a hail of missiles from Vile, who has apparently been resurrected from his earlier defeat in Mega Man X3. Vile has kidnapped Lumine for unknown reasons, and it becomes the Maverick Hunters' mission to rescue him.
However, what the Hunters do not know is that Sigma has returned once again, this time with his most ambitious plot yet. In Mega Man X7, it was revealed that Axl is the first of his kind, a prototype next-generation Reploid that has the ability to copy other reploids' DNA via a copy chip. In addition, these new Reploids have subroutines built in to prevent them from going Maverick. In X8, these next-generation robots have begun rolling off the assembly lines to work on the Jakob Project because they can copy strong Reploids, presumably at a lower cost than building the stronger Reploid itself.
Sigma's plan is simple. Contained on every single copy chip in these robots is Sigma's own DNA, meaning that the next-generation 'Maverick-Proof' reploids are in fact able to go Maverick at will. He seeks to scorch Earth to remove the "old generation" and repopulate it with his "children," a much more efficient method of domination than his previous attempts. What he did not count on was Lumine. When Sigma is defeated in his palace, Lumine steps in to take the entire operation over and kill the Maverick Hunters (it can be assumed he would have eventually tried this without the Maverick Hunters anyway). Lumine gloats to the Hunters that, in order for evolution to take its course, he and his fellow new-generation Reploids must destroy all that remains of the old world, both humans and "obsolete" Reploids alike. After a massive struggle, Lumine is defeated. When Axl walks up to Lumine's empty shell of a body, however, he is shocked as a tentacle springs from it and damages the crystal on his head.
As the three different characters ride back down the Jakob Elevator, Zero wonders if he no longer has to fight now that Sigma is dead for good, while X ponders Lumine's words on evolution. Axl is borderline conscious, but his shattered crystal can be seen glowing eerily with a tiny fragment of a mysterious purple crystal shard.