
In " Come Along With Me," wanting to stop the Gum War, Finn and Jake unleashed the nightmare juice given to them by Nightmare Princess, forcing them, Princess Bubblegum, Gumbald, and Fern into a hallucinatory slumber. He would later become infatuated with the dream version of Gunter, only to end their relationship after causing a premonition dream of Princess Bubblegum's foreshadowed usurpation in the Candy Kingdom. The Cosmic Owl makes a starring role in " Hoots," which reveals that he crashes in a cosmic motel and plays board games when he's not out making croak dreams come true. He soon leaves after they begin talking about the Citadel. When Jake and Finn return to the Time Room, the Cosmic Owl is seen wanting to play another round of Card Wars with a disgruntled Prismo. The Cosmic Owl makes an appearance in " Wake Up," at Prismo's party. The Owl tells him knowingly, "You blew it." After Flame Princess breaks up with Finn, the premonition is realized, and Ice King repeats the Cosmic Owl's message to Finn: "You blew it, man." At this point, Flame Princess and Ice King are engaging in a full-out war. Over the three dreams, the Cosmic Owl whispers something that Finn cannot hear, until the final premonition dream, where he stands directly in front of him. Three times, Finn attempts to experience the "cool" and "important" dream again because the Cosmic Owl is there. In " Frost & Fire," the Cosmic Owl appears in Finn's dreams, foretelling his inevitable break-up with Flame Princess.

At first, he is disappointed that he and Prismo could not play board games like they planned to, but he does join Jake and Prismo in the pool party. He also appears in " Jake the Dog," visiting his friend Prismo in the Time Room inside the Multiverse while Jake is making his wish.

The Cosmic Owl also appears in " The Lich," where he is seen in Finn's dream on a television screen, indicating that Finn is in a "premonition dream." The owl is also featured prominently on the episode's title card. He appears in " The New Frontier" at the end of Jake's " croak dream," and Finn and Jake's later conversation suggests that it is well known that the Cosmic Owl is supposed to show up in croak dreams.

It is stated that the Why-wolves, if not stopped, would ravage the world and overpopulate until the Cosmic Owl would be forced to intervene by devouring them all, as is the course of nature. The Cosmic Owl again appears in the episode " Donny" as a drawing made by the Why-Wolf. When Ice King asks why people do not like him, the Cosmic Owl answers, "You're a sociopath." Ice king does not care and calls him a big nerd. The owl first appears in " Prisoners of Love" in Ice King's Imagination Zone, after Ice King is knocked out by Finn.
