In Norse mythology, Ragnarok is a series of events including natural disasters, deaths of major gods including Thor, and a final battle that ends with the destruction of Asgard. However, the events following this apocalypse reveal a new and fresh world where the gods would eventually be reborn and watch over as humanity rebuilds and begins repopulating. While Marvel's Asgard saw and survived its version of Ragnarok, another Marvel universe wasn't so lucky. The Ultimate version of Asgard met its end at the hands of a futuristic army commanded by the Maker, a former hero turned villain who not only destroyed everything and everyone but ensured that it would remain that way permanently.
In this parallel Marvel universe, created to introduce modern audiences to classic characters by re-interpreting them in new and different ways contrary to their mainstream counterparts, the former his former Fantastic Four teammates. Last seen floating aimlessly in the Negative Zone, Reed managed to escape and upon returning to Earth, he puts together another experiment. He gathered a group of people and they spend a period of over 900 years in an accelerated environment called the Dome, evolving themselves to be nearly perfect super-humans called the Children of Tomorrow.
In the Ultimate Comics: Ultimates story-line 'The Republic is Burning' by writer Jonathan Hickman and artist Esad Ribic, the Dome reappearance interrupts a battle between Thor and the newly assembled Asgard is among the few forces in this world that can harm him and the Children. He orders Asgard and all of its citizens to be destroyed and depowered, immediately.
Unlike the apocalypse seen in Hickman's Ultimate Thor series, Asgard and its citizens put up a valiant effort but they are easily cut down and eviscerated by the Children of Tomorrow and their futuristic weapons. This massacre was not foretold in Norse legends or prophecy, this was an apocalypse brought down by science and ego because they were deemed too great a threat to ignore. Reed Richards continued his descent into infamy as the Maker with one of his most infamous decisions, the death of Asgard. Unfortunately, Thor arrives too late to save his brother Balder or his father Odin. He realizes that the World Tree may have hope and he steals his son Modi and imprisons him within the Room Without Doors, leaving the child in Loki's old prison with his trusty Mjolnir. Thor and Loki manage to pay their respects and apologize for their past indiscretions before they leap into battle for the last time together.
The Children of Tomorrow complete their destruction of Asgard by destroying the World Tree after draining it of its powers, killing many remaining Asgardians in the process, and leaving Thor powerless again. Although Thor would regain his powers (with help from Tony Stark) and help the Ultimates defeat the Maker and his Children, Asgard's demise would be permanent with no chance of resurrection. Thor would later learn that being the last son of Asgard meant his mind became a spiritual Valhalla, meaning spirits of the deceased Asgardians could manifest and offer him guidance. The fact that the Maker not only destroyed Asgard but also broke its cycle of death and resurrection permanently proves that an evil Reed Richards is a threat unlike any other and one that should not be underestimated, regardless of what universe he hails from.
