There are plenty of formidable Devils in the Chainsaw Man universe. Each of these monsters is capable of world-ending devastation if there's enough fear associated with their names. Some names that come to mind include the Gun Devil, the Devil Hybrids, the Four Horsemen, and the Primal Fears. However, fans have needed to speculate for a long time on the strongest Devil. A few concepts for a Devil among Devils were passed around, but nothing would be concrete without the author's input.
Source:https://www.cbr.com/chainsaw-man-death-devil/