"R'hllor." "The Lord of Light." "The Fire God." All of these terms are used interchangeably on Game of Thrones, but many fans still aren't sure exactly who this mysterious deity actually is. If you're one of them, don't worry: the night is dark and full of answers about this confusing religion from the series.
The religion of R'hllor is based out of Essos, where fire priests and priestesses (like Melisandre) train in their faith. The faith has many facets, but it boils down to this: light and darkness are intertwined and cannot exist without one another. The Lord of Light is just that: a god of light and warmth, eternally facing down another entity of darkness, cold, and death. This is why so many worship practices involve fire — it banishes the cold and darkness by creating warmth and light in the image of R'hllor.
Unlike the polytheistic beliefs of other Westerosi faiths like The Seven and the Old Gods, prophets of R'hllor reject the idea of any god but their own. While many citizens of the Seven Kingdoms are skeptical of the Fire God, we have seen proof over the course of GOT that he exists. Remember the demon shadow baby that assassinates Renly Baratheon, or how Jon Snow is brought back to life? There's no denying that R'hllor is powerful, even if we haven't actually seen the god manifested physically.
A few notable believers from the series include Melisandre, Thoros of Myr, Beric Dondarrion, and — recently, thanks to a vision in the flames he fears so much — Sandor "The Hound" Clegane. Because the religion is so brutal in its sacrifices (RIP Shireen) and its harsh attitude toward nonbelievers and false gods, it's not exactly broadly appealing . . . but perhaps a powerful god of light and fire is exactly what's needed to combat the cold and darkness of the Night King and his cronies Beyond the Wall. Could R'hllor be the answer to defeating the White Walkers? Only time will tell!