All of Harlan Ellison’s stuff is good, but this one is probably one of the most disturbing sci fi short stories of all time. As a note, this version isn’t the best, so you may be able to find a better one.
“I Have No Mouth & I Must Scream” originally appeared in IF: Words of Science Fiction, March 1967; ©1967 by Galaxy Publishing Corporation. Copyright reassigned to Author 3 December 1968. © by Harlan Ellison.