(n.) A maker of scholia; a commentator or annotator.

allegorist annotator book reviewer captious critic carper caviler censor censurer cicerone clarifier cognoscente commentator commenter connoisseur critic criticaster criticizer critickin criticule cryptanalyst cryptographer cryptologist decoder definer demonstrator demythologizer diaskeuast dragoman editor editorial writer editorialist emendator emender euhemerist exegesist exegete exegetist explainer explicator exponent expositor expounder faultfinder glossarist glossographer go-between guide hermeneut interpreter leader writer lexicographer literary critic man of letters metaphrast muckraker news analyst oneirocritic paraphrast publicist reviewer smellfungus social critic textual critic translator