Mr. Fox first appears in the episode "Storytelling." Finn forced him and Boobafina to kiss for a touch of romance in Jake's story. Afterward, it is revealed that Mr. Fox had a crush on Boobafina all along and wanted to kiss her. Finn starts to think that he helped Mr. Fox, who then says she will never like him because they needed to kiss naturally. Later, Finn tells Mr. Fox that "Boobafina is not interested. It's time to move on." Mr. Fox is sad to hear this, but accepts that Finn is right. It is unclear if the two are still friends. He is one of the many animals present at the Rite of Forest Justice.
He also appears in "Another Five More Short Graybles," in which he shows his home to the audience, describing its components and discovers that his subconscious self was writing a treasure map for him.
In "Astral Plane", Finn's Astral self visits his home for a few seconds, in which Mr. Fox's astral self is in a chair doing a Sudoku puzzle, while his physical body is sleeping, talking about Boobafina in his sleep. He offers Finn a drink, either forgiving him for ruining his chances with Boobafina or not remembering him at all, but Finn beyond his control leaves for the next location which Mr. Fox deemed "sorta rude."
Mr. Fox looks like his namesake. He can walk on two legs, but runs on four. He has bags under his eyes, but that could be because he was constantly stressed throughout the episode "Storytelling."
His new form, Mr. Death, appears rather similar to Death. However, instead of a horse skull, Mr. Death's skull resembles that of a fox, and he wears a taupe bathrobe with cream-colored trims, pink bunny slippers, and Death's hat. He also has a pillow, and can conjure as many as he needs to so the souls that reside with him can know blissful peace and rest.
See: Mr. Fox/Quotes
- "Wizard Battle" (cameo)
- "Jake the Dad"
- "Ocarina" (cameo)
- "Astral Plane"
- "The Comet" (comet projection)
- "Angel Face" (no lines)
- "King's Ransom"
- "Do No Harm"
- "Winter Light"
- "Skyhooks II"
- "Come Along With Me"
- Mr. Fox is the second character to have a subconscious that can touch the material plane. The first is Jake.
- In "Astral Plane", both Finn and Mr. Fox seem not to remember each other at all. While it is understandable for Finn, as he only met him once, Finn was the one who ruined Mr. Fox's chances to be with Boobafina, in which that same scene showed that he is still heartbroken over her. Or rather, Mr. Fox does remember, and was being hospitable due to all the animals having forgiven Finn at the end of "Storytelling" for better or worse. Regardless, after Finn left, Mr. Fox hoped he would return, likely due to being incredibly lonely, which Finn points out immediately afterwards.
- Mr. Fox is stated to be incredibly lonely, and is even hinted at in "The Comet" to be the loneliest being in Ooo. Despite "Jake The Dad" revealing that he has an entire family or group of foxes with whom he associates. However, it could be implied that he may have alienated himself from the rest of his gang/tribe after his plan utterly failed and humiliated them all.
- In "Ocarina" he is one of the many renters, purchasing board at Finn and Jake's home, despite the fact that he is shown to have his own house in "Another Five More Short Graybles", "Astral Plane", and "King's Ransom".
- It is said that his voice is based upon a poor Christopher Walken impression from one of the creators.
- In "Come Along With Me", his skull can be seen in BMO's house on Mount Cragdor in the future, when Beth picks it up and drops it.