Patrick Danville (first appeared in Insomnia)

Patrick Danville (b. 1989) was the son of Sonia Danville. When he was a child, he dreamed of Roland Deschain and the Crimson King; in October of 1993, he drew a prophetic picture of Roland and the King at the Dark Tower. On October 8th, 1993, he attended a Susan Day rally with his mother at the Derry Civic Centre; due to the efforts of Ralph Roberts, he and his mother survived Ed Deepneau's attempt to crash a plane into the building.

Patrick Danville is mentioned in the following books:

The Dark Tower VII: The Dark Tower (Sep 2004)

Nancy gifts Roland Insomnia, by Stephen King, and warns him that Patrick Danville may have an impact on his quest.

Nancy said, “In the story, the Crimson King is using Ed Deepneau to kill one single child, a boy named Patrick Danville. Just before the attack, while Patrick and his mother are waiting for a woman to make a speech, the boy draws a picture, one that shows you, Roland, and the Crimson King, apparently imprisoned at the top of the Dark Tower.”
- Part 3 / Chapter III / Section 11

Duma Key (Jan 2008)

A subtle connection, but both Edgar and Elizabeth have the ability to remove things from reality by painting and erasing them - the same as Patrick Danville in the Dark Tower.

“Take it easy, muchacho,” Wireman said. “Go slow. She tried to draw Perse out of existence. How does one do a thing like that?” “Draw and then erase.” “Perse didn’t let her?”
- Part 15 / Chapter 13