Hyperstorm is a time-space conqueror of vast cosmic power, operating within the Marvel Multiverse and targeting in particular what was until 2015 the main Marvel Universe, Earth-616. He was in particular an enemy of the Fantastic Four, a fact which would prove to be very ironic indeed
Hyperstorm was born Jonathan Reed Richards in a future alternate to not only the main Marvel Universe, but to the Sentinel-dominated 'Days Of Future Past' world. Unlike most such scenarios, Franklin Richards, first child of Reed and Susan Storm Richards, lived long enough to marry and have a child with Rachel Summers, daughter of Scott Summers and Jean Grey. Franklin already possessed the power to alter reality itself, and in some versions, it is intimated that Rachel is the daughter not of the Human Mutant Jean Grey, but of the disguised Phoenix assuming her form. Taken together, Jonathan had an almost literally stellar lineage, grandson of two alpha mutants, a woman whose force field powers are said to derive from hyperspace, and one of the most brilliant minds in all of history. At some point, Jonathan's parents were killed by the Sentinels, but it is unclear if this specifically is what drove him to villainy. He did decide to unite the world in peace, though under his absolute rule in all things.
Perhaps following the model of Kang, who in some texts is also of the Richards' bloodline, Hyperstorm began amassing a time-space empire. The counterpart to his great-grandfather, Nathaniel Reed Richards, also became a time-space traveler and learned of the threat his descendant posed. Returning to his birthplace of Earth-616, he attempted to warn his son Reed's team of the threat Hyperstorm posed, a threat made real when the then-supposedly dead Reed and Victor Von Doom were found to be alive but held by Hyperstorm. To try and avert the threat Hyperstorm's eventual all-out assault would pose, Nathaniel assembled a group called Fantastic Force, led by a time-aged Franklin. Nathaniel's penchant for secrecy and hidden plans proved even greater than his son's, alienating almost all his would-be allies. In a flash, Hyperstorm showed his power by casually undoing the older Franklin's timeline, reverting him to childhood. When his all-out assault began, only then was his heritage revealed, and his power proved predictably unstoppable. Reed managed to send Hyperstorm into a dimension where Galactus had placed himself, and there the starving World-Devourer drank endlessly of Hyperstorm's power, creating a loop that locked them both. Galactus has been seen since; Hyperstorm has not.
The limits of Hyperstorm's power may be immeasurable. The heir of so much power, including reality-warping, hyperspace manipulation, the brilliance that runs in the Richards' line and very possibly the Phoenix Force itself, he was only able to be contained by one of the prime powers in all the universe, and then only contained, not killed or destroyed.