The Tongue Monster is a resident of Monstropolis that enjoys eating at Harryhausen's. He is a pale-skinned monster that appears to consist of two separate entities; one personality controls most of the body, while the second performs the roles of a tongue, and seems to require its own food.
The Tongue Monster was enjoying a meal at Harryhausen's on the night of Mike Wazowski and Celia Mae's special date. Once James P. Sullivan arrived at the restaurant requesting assistance from Wazowski, the human child that was stuffed inside his duffel bag got loose, causing panic to everyone inside. The CDA arrived quickly to shut down the restaurant and investigate, forcing the Tongue Monster and everyone else to leave the restaurant.