I Feel Sick is a comic book created by artist Jhonen Vasquez, with colors by Rosearik Rikki Simons. Published in August 1999 through May 2000, it is a spin-off of Vasquez's comic book series Johnny the Homicidal Maniac. I Feel Sick revolves around Devi D, who first appeared in Johnny the Homicidal Maniac. In the book, Devi, a graphic designer, must face the supernatural and psychological forces that drove Johnny C. to lunacy.

Published by Slave Labor Graphics, it was originally intended as a single paperback but was split into two issues. Vasquez said the creation process of I Feel Sick was cathartic. Devi's problems working for Nerve Publishing and neglecting her own work are reminiscent of the pressure Vasquez experienced working on Invader Zim, an animated television series he created for Nickelodeon.