Which of the following was the author of "Username Evie"?

The author of "Username: Evie" is indeed Joe Sugg. Joe Sugg is a British YouTuber, vlogger, and author known for his online presence and collaborations with other popular YouTubers. "Username: Evie" is a graphic novel series created by Joe Sugg, featuring a young girl named Evie who escapes into a virtual world after facing difficulties in her real life. Joe Sugg's involvement in the creation and promotion of the book series makes him the correct answer to this question.