Einherjar Eight Warriors

The Einherjar Eight Warriors (アインヘルヤル八闘士) are a group of eight Mutos Reploids that replace the Eight Gentle Judges in Mega Man Zero 4. They are commanded by Craft, and they were tasked by Doctor Weil to destroy Area Zero with a variety of high-tech weapons:
 * Sol Titanion took control of an artificial sun, turning the surroundings into a desert wasteland. Zero weakens the sun's functions by destroying its generators and shuts it down for good when he takes down Titanion herself.
 * Heat Genblem uses his own body to power a mobile particle cannon headed towards Area Zero, periodically firing devastating beams to ravage the landscape. After Zero infiltrates the weapon by going through its barrel, he destroys Genblem, which also leaves the cannon without a power source, ending its threat.
 * Popla Cocapetri infects an ancient mechanical city with a computer virus, intent on using it as a frontline base against Area Zero. Unfortunately for him, Zero is able to fight through the city's automated defenses and destroy the diminutive Reploid.
 * Pegasolta Eclair pilots a massive aerial fortress towards the Settlement, using acid rain to kill the plant life below. Zero invades the fortress, destroying the generators responsible for the lethal precipitation before doing the same to its Einherjar commander.
 * Mino Magnus activates a massive electromagnetic generator, creating magnetic waves that begin to disrupt the surrounding area. His plans never reach the Settlement, as Zero fights his way to the generator and destroys Magnus, stopping the waves from wreaking havoc.
 * Noble Mandrago uses plant-like nanomachines to overrun the natural wilderness of Area Zero. In turn, Zero cuts through the false jungle to reach the Reploid controlling it, who he destroys in battle shortly afterwards.
 * Tech Kraken causes earthquakes with a drill-equipped submarine, threatening to demolish Area Zero and the Resistance Base. Navigating a complex maze, Zero confronts Kraken, who reveals his ulterior motive for joining the Einherjar: defeating Zero to avenge his late master, Phantom. Nonetheless, the red Reploid defeats the Zan-ei soldier, ending his part in Weil's plot.
 * Fenri Lunaedge reactivates a facility containing old, potentially dangerous experiments. Zero overcomes the security and rogue projects on his way to the building's final chamber, where he destroys Fenri and shuts down the facility.

Unknown to Zero, Ciel, the Resistance, and the Settlement, the Einherjar are simply a distraction for Dr. Weil to complete Ragnarok. Once the Eight Warriors are defeated, Weil reveals this horrifying news to Zero and all the others at the Settlement, forcing Zero to travel to Ragnarok to stop Weil. Suddenly, Craft arrives and destroys Ragnarok's remote control system, and recalibrates the targeting mechanism so that Ragnarok is aimed directly at Neo Arcadia, and Dr. Weil. Craft manages to fire before Zero can stop him, and Neo Arcadia is obliterated by the might of Ragnarok. Luckily, Colbor Team of the Resistance was able to evacuate most of the residents of Neo Arcadia thanks to a warning recieved from Ciel, except for the area around where Weil was located.

Trivia

 * In Norse mythology, the einherjar are those that have died in battle and are brought to Valhalla by valkyries. They prepare daily for the events of Ragnarök, when they will advance for an immense battle.