The Case Files of Lord El-Melloi II is a Japanese light novel series written by Makoto Sanda and illustrated by Mineji Sakamoto. Officially part of the Fate series, it began serialization by Type-Moon under the Type-Moon Books imprint on December 30, 2014, to May 17, 2019. The novels are set between the events of Fate/Zero and Fate/stay night, focusing on Lord El-Melloi II, a former master who now investigates several mysteries after his participation in the Fourth Holy Grail War. A sequel novel series, The Adventures of Lord El-Melloi II , began publishing on December 25, 2020.