Shadowguy, @theshadowguy on twitter, was a member of the chatrealm and the super secret <> club. He was also a huge fan of NSFWshow, Scam School, Weird Things Podcast, and many other awesome things. He watched every episode of NSFW and tried to catch the super secret <> shows whenever possible, which had been getting harder for him when Brian discovered the justin.tv app and streamed all the frigging time. Shadowguy enjoyed anime and television shows and would talk at great lengths about them on twitter, @ replying anyone who mentioned something anime or TV related.
Shadowguy made a brief cameo in Chapter 5 of DIAF as Guy of Shadows.
Unfortunately he recently died, because if you make your own BBpedia entry, TPIA.