Warning! Spoilers for Justice League: Endless Winter Special #1 below
The Justice League's next threat has been revealed and the new villain has a shocking Kryptonian connection. In the new DC Comics event Endless Winter, the massive monster named the Frost King has appeared and immediately started trying to turn everything and everyone into ice. Surprisingly, its existence can be directly tied to Superman's old Fortress of Solitude.
Superman's Fortress of Solitude has been the longtime headquarters of the Man of Steel, as it's his secret hideaway that's he can get away to find solace. It also serves as a place where Superman can keep important items hidden - including the bottled city of Kandor. However, in Brian Michael Bendis' Man of Steel arc, the Kryptonian hunter Rogol Zaar invaded the fortress and destroyed Kandor, leaving Superman no choice but to destroy his hideaway (his new fortress was built in the Bermuda Triangle). It turns out, Kal-El didn't do a good enough job cleaning up after himself, as Kryptonian crystals from the destruction of the fortress have led to the creation of a new villain.
In Justice League: Endless Winter Special #1 by Ron Marz, Andy Lanning, Howard Porter, Hi-Fi, and Andworld Design, Stagg Industries, led by Sebastian Stagg, are seen in the arctic, excavating the spot where the Fortress of Solitude used to be. Stagg lies to his board about the true nature of his dig, telling them his research shows him the ice holds the key to "cold fusion" which could help the company dominate the clean energy market. It's soon revealed his true plan is to dig up the leftover crystals from the Fortress of Solitude to help unlock Kryptonian secrets. However, their dig takes an immediate left turn when they inadvertently free a new villain called the Frost King.
With the Justice League on the scene, none of the heroes recognize the villain. The Frost King summons hordes of ice monsters to attack the superteam and when Superman arrives to help, the monster unleashes a power that envelops the entire Earth in snow. Kal-El soon realizes he might be at fault for the Frost King's creation as he figures out they're at the same location as his old fortress. He picks up a Kryptonian energy signature from the Frost King and notices the ice has been fused with the crystals he left behind. It's bad news.
In just a few pages, the Frost King shows its massive power, that's fueled by absorbing Kryptonian crystals. The new villain is going to be quite the threat for Superman and the rest of the Justice League as who knows his upper-limits of powers as a literal Kryptonian-infused frost giant. We'll find out how Superman and co. respond as Endless Winter continues in The Flash #767.