Warning: contains spoilers for Fantastic Four #45!
The Fantastic Four's most recent event is finally over - and the conclusion draws a major parallel between the Marvel and DC Universes. The entire universe is at stake during the Reckoning War, in which a new enemy that previously lost a universe-wide war against the Watchers reemerges to threaten all reality. In Fantastic Four #45, writer Dan Slott introduces a DC concept to the Marvel Universe: the Source Wall.
In the Reckoning War, a fifteen-year plan finally comes to fruition when the Prosilicans, now calling themselves the Reckoning, emerge from an unknown corner of the universe to see revenge against the Watchers. The war between the Watchers and the Reckoning ended when the Watcher Enmu fired the Ultimate Nullifier, rendering nine-tenths of the universe uninhabitable. The Watchers believed they were victorious, and vowed from that point forward never to interfere in the affairs of other beings - instead, they would use their powers to observe and record history.
In Fantastic Four #45, written by Dan Slott with art by Farid Karami, the entire narrative comes to a head after Watcher-powered Reed Richards uses the power of the Ultimate Nullifier to defeat Wrath (the leader of the Reckoning) while also removing the Watcher portion of his brain that he absorbed at the beginning of the event. Meanwhile, Uatu the Watcher uses the collective power of the other Watchers to undo all the damage caused by his species' interference. He reassembles Earth's moon, teleports all participants to their rightful places in the universe, and brings down the barrier separating nine-tenths of the universe. The barrier is eerily similar to the legendary DC Comics' Source Wall.
In the DC Universe, the Source Wall is a quasi-mystical barrier surrounding the Multiverse, and the mysterious Source of All Creation itself lies beyond it. The Source Wall is a creation of Jack Kirby during his work on the Fourth World and the New Gods, and is rarely seen in modern-day DC Comics. Few characters can find it, and the Wall itself is partially made out of Promethean Giants (cosmic beings and anyone who dares try to breach it). Behind the barrier lies a mystery not unlike the one behind the "wall" erected by the Watchers - but while one is almost God-like in nature, the other is created by the Watchers as a solution to a bitter war.
A great barrier cutting off a massive part of the universe is not a new concept, but the one seen in the Reckoning War is quite similar. DC's creation myths are slightly more defined than the Marvel counterparts (though both the One Above All and the Presence, the Marvel and DC's God equivalent, are seen occasionally) and are quite complicated when reading the Fourth World material. Nevertheless, the Fantastic Four's event ends with the barrier falling, but the DC's Source Wall is still active.