Supernatural: 10 Biggest Unanswered Questions
4. What Happened To The Other Horsemen?
The Four Horsemen of the Apocalypse arrived in Season 5 in the wake of Lucifer’s arrival. A group of enormously powerful entities that embodied the four prime concepts that drives the Apocalypse, each Horseman uses a special ring to channel their core ability - without which, their physical forms are lost, excluding Death.
When Lucifer rises from his cage in Hell, he takes command of the Horsemen and directs them to start his genocide against humanity. When Sam and Dean figure out the rings the Horsemen wore were also the keys to opening Lucifer's cage, they stole them all by force, apart from Death who willingly gave his over to Dean.
Although Death became a reoccurring character of the series - returning multiple times and even being replaced with the reaper Billie - Famine, Pestilence and War never returned after their respected episodes.
Once the four rings were used to open the portal to Lucifer’s cage, we never heard what happened to the other three Horsemen. Wouldn’t they try to track down the Winchester brothers to try and retrieve their rings that were taken from them? Since these beings were (at the time) above the boys' paygrade, a final showdown between the Winchesters and the remaining Horsemen would have made for a great watch and ended the Horsemen storyline nicely.