Cockmongler is a 4chan reaction image of a red-haired man striking an exaggerated pose with an unusually wide, toothy grin, taken at a Canadian tourist attraction1. On 4chan it became one of the oldest reaction images on the site and is often photoshopped into other pictures and scenes4. Longtime posters treat the character as an unofficial mascot of the imageboard3.

The name itself picked up other slang uses on Urban Dictionary, where entries list it as a fake nickname for the grinning man or as a term for someone who constantly touches themselves2. On /b/, the image is also posted under variant nicknames like 'Grinman' or 'Smiling Man' as intentional misidentification bait3.