Maerlyn, also known as the Ageless Stranger (or Legion) in the original publication of The Gunslinger, is a powerful sorcerer and a demon of the Prim. He is described as being a rogue wizard and is often associated with Arthur Eld. Some believe he appeared with loyal followers uninvited to Arthur's coronation and offered him the Wizard's Rainbow, and that it was this turn of events that led to Arthur's impregnation of the Crimson Queen and the birth of the Crimson King.
As a spawn of the Prim, he cares nothing for order, stability or logic. He relishes chaos, creating havoc for his own amusement. Disguised as a grey-bearded Wizard, he convinced the Great Old Ones to build Dogans, where they fused technology with magic. Later, he convinced the corporation North Central Positronics to claim supreme ownership over the space-time continuum by replacing the Dark Tower with one of their own making, which eventually led to the downfall of the Old Ones.
He was content with the destruction he had caused until Arthur Eld began to rebuild the world, and so from his subterranean home at the edge of the Prim he spun the Wizard's Rainbow. At some stage he used the magic of the Prim again to make The Laughing Mirror. He visited the town of Brockest and convinced the inhabitants to forsake Gan and worship the ancient can-char by sacrficing one of their own to them.
According to the comic, "The Gunslinger Born #2", he was a demon who took the form of an old man. He created thirteen magical balls, which are named Maerlyn's Rainbow.
Role in The Dark Tower Series
The Wind Through the Keyhole
In The Wind Through the Keyhole, Tim Ross seeks Maerlyn out after being shown a vision by The Covenant Man of Maerlyn giving Tim an item to cure his mother's blindness (which occurred after she was beat by her new husband, Bern Kells).
After Tim's journey he comes across a cage with a tyger in it. Tim sets the tyger free, and gives it shelter while a Starkblast passing over them. In a box left for him by The Covenant Man, Tim finds a vial, some of the liquid he gives to the tyger (Tim thought the tyger sick, and the liquid medicine). The tyger begins to transform and eventually becomes Maerlyn.
Maerlyn talks to Tim and tells him that he was caught off guard when he was drunk and trapped in the cage by an emissary of the Crimson King who posed as a wandering peddler, and since The Covenant Man sent Tim to Maerlyn the Crimson King will punish him for causing the release of his prisoner. He goes on to tell Tim that the Crimson King is trapped on a balcony outside the Dark Tower, and disregards some of the rumors people speak of himself. Before departing he tells Tim to take the rest of the vial to his mother and pour the liquid in her eyes to cure the blindness. He also tells Tim to give his father's old axe to his mother as well.