Gan

“I’ll stop when you speak true. Do you know—” “Yes, all right, I know what you’re getting at. Satisfied?” “Not yet. Tell me what—” “I’m Gan, or possessed by Gan, I don’t know which, maybe there’s no difference.” King began to cry. His tears were silent and horrible.

Entity whom the fictionalized King believes is speaking through him, matching the established Tower cosmology.

It was the Tower’s voice. This edifice was not stone at all, although it might look like stone; this was a living thing, Gan himself, likely, and the pulse he’d felt deep in his head even thousands of miles from here had always been Gan’s beating life-force. Commala, gunslinger. Commala-come-come.

Divine presence Roland perceives through the living Tower; the identification remains Roland's interpretation.