Encounters in the moathouse (Dave Trampier, AD&D module T1: The Village of Hommlet by Gary Gygax, TSR, 1979)  

For years I wondered what was that giant one-eyed grinning thing in the funny hat on the right.  When I got my own copy I flipped through looking for a description of an ogre-cyclops-demon.  Finally I realized it was a just a human cleric with an eye badge on his surcoat, like the guards on the left, but oversized to show his importance like a figure in a medieval manuscript.  I still have to force myself not to see it as a goofy cyclops.