The Graknil specimen featured was a yellow-spotted, green mass about twice as large as Spiff. It had tentacles for legs, a forked tongue and a piglike snout. Spiff encountered it on Planet Zorg, and considered it hostile.
Graknils also appeared once in a strip where Spiff was trapped in an alien spaceship. He then bolted for the airlock, which was his classroom window. Mrs. Wormwood caught him just as he went out the window, saying, "Nice try Calvin."