Rick + Morty in the Eternal Nightmare Machine (also stylised Rick and Morty in the Eternal Nightmare Machine, or simply Eternal Nightmare Machine) is an American pixel-animated short film based on the television series/franchise Rick and Morty, produced by Adult Swim and debuting on both the network and their YouTube channel on April 30, 2021, alongside a marathon of the series' fourth season, to promote its then-upcoming fifth season. Written, directed, and animated (in the style of a 16-bit video game) by Paul Robertson, the film received positive reviews from critics.