According to Doomworld forum regular Marnetmar, Callum Guy Oliver aka "phobosdeimos1" passed away earlier this year. He was a newcomer to the Doom community in 2011, releasing a number of works and participating in several community projects, including Interception, Panophobia, and Doom the Way id Did. Though none of his entries made the cut for the first DTWiD release, project lead Xaser is compiling them for a posthumous solo WAD, along with perhaps any as of yet unreleased material. I know a third episode of his Raw Action series was in the works; perhaps it may still see the light of day.
While I've played works from authors who had previously passed on (most notably Esa Repo), I haven't had an author I've enjoyed die, until now. Oliver tended toward abstract layouts that emphasized map connectivity and lots of action, with the majority of his work featuring techbases. From what I can gather, he got most of his inspiration from Sandy Peterson.