Every Villain The Arrowverse Has Teased But Not Used

DC's answer to Galactus, the universe-threatening Imperiex made his bow in 2001's Our Worlds at War crossover. The embodiment of entropy itself, Imperiex detected an imperfection in the universe and sought out to destroy and remake it. His plans were foiled by a coalition of DC powerhouses such as Superman, Darkseid and Martian Manhunter.

The cosmic despot was mentioned in Legends of Tomorrow's first season when (then) Captain Rip Hunter invokes the 'Imperiex Onslaught', a code phrase designed for the ship AI Gideon used in emergency situations. This implies that a being known as Imperiex existed in the Arrowverse, but it was never made clear if they were similar to the comics rendition of the character.

Adapting Imperiex to the small screen would be a tall order for the Arrowverse, and his storyline would easily rival Crisis on Infinite Earths in terms of scope and sheer number of characters. That said, exploring the revelation that Imperiex was the imperfection he did would make for an intriguing twist in a potential adaptation.