October 23

October 23, and the number 23 alone, are significant in Nathaniel J. Nelson's writing.

Erogrendel

 * Both Nick McMann and Mark Tenant die on October 23, 2014 and 2015 respectively.
 * Protagonist Olivia Cambridge is twenty-three years old.
 * Detective Isaac Parry carries a Glock 23.
 * The Mist of Time by Sirichai Jones is 1,023 pages long.
 * Mark Tenant and Richard Marvin leave the Seventh Circle office "twenty-three hours" since Olivia's attack.

Quantum Flight 888

 * Eva Van Savage, a point of view character in Quantum Flight 888 was born on October 23, 1988
 * Joshua Teller's acceptance letter to the University of Southern California was dated October 23, 2004.
 * Row #23 of the plane is referenced.

I Am Halloween
In I Am Halloween, the titular being refers to October twenty-third as "My Day," and describes it as "A day of great power, when the walls between the physical and the supernatural grow thin and pliable." He goes on to claim that "Evil was released into the world on the twenty-third of October," and that "An insane, power-hungry beast managed to doom her entire species on that day." Prior to the settling of humans, the narrator and his supernatural friends would experience a rush of drug-like euphoria on this day every year. Late in the story, the narrator comes to believe that the supernatural nature of the day has shifted to October 31, due to the humans celebrating it as a supernatural-based holiday.

The Number Four

 * Brenna travels back in time to 1923.