Satoshi Wagahara is a Japanese male light novelist known for creating the popular series The Devil Is a Part-Timer!. He was born in December 1982 and currently resides in Saitama Prefecture. His professional writing career began after he won the 17th Dengeki Novel Prize silver award in 2010 for his manuscript titled Maōjō wa Rokujō Ikkuma!. This winning entry was retitled and published as the first volume of The Devil Is a Part-Timer! light novel series, which was released by Dengeki Bunko in February 2011 and marked his official debut as an author.

Wagahara is best known as the original creator of The Devil Is a Part-Timer! franchise. The central story follows Satan, the Demon Lord from the fantasy world of Ente Isla, who is forced to retreat through a gate to modern-day Tokyo after being confronted by the hero Emilia. Stranded on Earth without magic, he adopts the human identity Sadao Maou and begins working at a fast-food restaurant called MgRonald's to survive. The original light novel series concluded after 30 volumes, running from February 2011 to August 2020.

Beyond the original novels, Wagahara has overseen multiple manga adaptations of his work. A manga version illustrated by Akio Hiiragi began serialization in Dengeki Daioh in December 2011. He is also credited as the writer for the spin-off manga The Devil Is a Part-Timer! High School!, which was illustrated by Kurone Mishima and ran in Dengeki Maoh from May 2012 to February 2015. Another spin-off, Hataraku Maō-sama no Meshi! (The Devil Is a Part-Timer! Official Anthology Comic), illustrated by Oji Sadō, was published from August 2019 to November 2022.

The franchise has been adapted into anime on multiple occasions. The first season, produced by White Fox and directed by Naoto Hosoda, aired for 13 episodes from April to June 2013. A second season, produced by Studio 3Hz and directed by Daisuke Tsukushi, aired in two parts from July to September 2022 and July to September 2023.

In addition to his flagship series, Wagahara continues to produce new work. He published a new light novel titled Dracula's on the Night Shift in December 2024. He also provided a comment for the anime series YOUR FORMA, offering reflections on its futuristic themes and expressing particular fondness for a character named Fluffy.