The Deadlights are writhing, radiant orange lights that are a mysterious but very deadly and terrifying, eldritch form of energy originated from the preternatural dimension known as the Macroverse (also known as the Todash Darkness) and a recurring plot element from the works of legendary horror writer Stephen King including The Dark Tower and Stephen King's IT. It is well known one mere glance (no matter a living soul stares briefly or longer) into these bright lights can instantly cause death and permanent insanity.
- Crimson King: The dreaded dark lord, the Crimson King himself, wields the Deadlights, which is also referred to as a type of magic. The Deadlights, when used, are able to cause great suffering to the point of death, and even possibly do things to the affected victim's soul. The Crimson King uses the Deadlights around the once cursed American town of Derry within Maine, in the book "Insomnia" to ascend to another level of the Dark Tower, but yet never directly casts "deadlights" as any sort of sorcery himself)
- It/Pennywise the Dancing Clown: The very life essence and even true form of the dangerous extradimensional beast IT is comprised of the Deadlights themselves and It uses this power to blind his fresh victims (usually human children) and robs them of their conscious minds as It drives them crazy as well as leave them both immobile and lifeless before It takes them away and consumes them. In the 1990s TV miniseries Stephen King's IT, in 1960, the murderous local bully Henry Bowers witnessed It's Deadlights after his recent failed attempt to kill Stan Uris of the Lucky Seven and survived, but ended up being insane while his hair turned pale white as a side effect of the Deadlights' power, before he emerged from the sewers beneath Derry and immediately arrested by the police for the deaths of the children taken by It which he confessed of while in custody. Also, in the 2017 It remake, Beverly Marsh witnesses the Deadlights and is put into a temporary coma. She is brought out of the coma by Ben Hanscom kissing her. Upon looking at the Deadlights, Beverly and to an extend the audience hear multiple sounds of children screaming. Including an older person shouting "HELP ME!!!" This implies that the Deadlights and to an extension It, doesn't just eat their flesh and fear, but their souls as well.