Dean McCoppin Mug is a reaction face based on a still image of Dean McCoppin from The Iron Giant, holding a mug of coffee with a smug grim on his face. Over the years, numerous derivatives have been made, starring various characters from different franchises.
The shot of the character was taken from a scene in the film “The Iron Giant”, which was released in August 6th, 1999. The image since then has been modified and used as a reaction image. The earliest documented usage of it can be dated back to June 1st 2009 on 4chan‘s /tg/ (Traditional Games) board , in a thread discussing techpriest and psyker melee capabilities in Warhammer 40K.
Over the years, many images, which include various characters from different franchises, were created based on this picture, all of which include the character holding a mug of coffee and usually having the same facial expression as Dean in the film.
One of the more notable variations features a representation of a Warhammer 40K Space Marine from Blood Raven chapter. Because of the fact that, in universe, they are represented as tech-hoarders, in each different version of the image the Space Marine holds a different mug.