Who is the male investigator on the cover of Arkham Horror, Elder Sign, and Eldritch Horror?
Honestly, I think it's just 'Generic 1920's stereotype'.  While I agree that he's got a tommy gun in both pictures, his facial structure looks wrong for being Michael McGlen.  He actually looks closer to Joe Diamond, if it wasn't for Joe Diamond having a blue suit.  Michael McGlen would be closest, without going over, but I think the cover art characters are just generic characters and no actual investigator.