The Muslims have never had a big, convoluted End Times mythos like the Christians, at least not in the Qur’an. At some point in the indefinite future, there will be Judgement Day, and everybody living or dead will get hauled in front of Allah and the recording angel will play back your scorecard. Then it’s Jinnah (heaven) or Jehenna (hell).
There are quite a number of hadiths (extra-scriptural reports of things Muhammad said or did) that talk about the end times. Hadiths are assessed by Islamic scholars based on their provenance and general credibility. Those originating from people close to the Prophet are ranked higher; those that contradict the Qur’an are downgraded. Most of the non-Qur’anic end times narratives sound very similar to Christian eschatology, except that the Mahdi, the successor prophet to Muhammad, appears. Jesus (Issa) returns (and maybe he’s the same guy as the Mahdi?), there’s the Antichrist (the Dajjal) stirring up mischief, there are signs and portents, the giants Gog and Magog running amok, the stars fall from the sky as meteors, etc, etc.
It’s not as entertaining as Ragnarök, but it’s more coherent than the Christian fundies’ fanfic.