Poison Mushroom Cookie

Some mushrooms are good for your health, and some aren't. Take the purple-capped mushroom, for example. How appetizing and delicious it looks! That's why that hungry cookie ate it. Yes, that was the Poison Mushroom Cookie. Always calm, always daydreaming. Before, the Poison Mushroom Cookie was mistaken for a real mushroom, but they never got angry, never! The Poison Mushroom Cookie would greet and hug those confused cookies as if they were old friends, that's right! She would offer each one a mushroom of her own: so sweet, so colorful. Just one bite, just one... After all, those big, friendly eyes don't bode well for any harm. No harm at all...

The Poison Mushroom Cookie is a very small cookie with dark brown dough, wearing a dark purple robe with long, periwinkle-striped sleeves. It also has what appears to be a giant purple mushroom cap on its head, with fuchsia spots. Its mouth is jagged and zigzag-shaped, and it has sunken purple eyes.

In an early design concept, Poison Mushroom Cookie had a more skull-like motif, particularly in its head; its face and cap were positioned to resemble a human skull, with an irregular, W-shaped mouth reminiscent of a stylized alveolar process and upper row of teeth. Although the skull motif was almost entirely removed in the final design, its peculiarly shaped mouth is likely a remnant of this earlier design.

Poison Mushroom Cookie serves as a subordinate to Dark Sorceress Cookie, carrying out tasks assigned by her or by Poison Cookie. However, despite being under their service, Poison Mushroom Cookie seems to lack malicious intentions or even knowledge of his group's activities. Instead, he acts in a childlike and playful manner, accepting even defeat with fortitude and befriending everyone he meets, even those he supposedly opposes. He seems to get along particularly well with Licorice Cookie, accompanying him in his evil schemes. Poison Mushroom Cookie is very eager to share his mushrooms with his Cookie friends, seemingly unaware of the harmful effects the fungus has on normal Cookies, something other members of the Dark Cookies often take advantage of. In the Eternal Kingdom episode, Licorice Cookie forced them to use one on Pure Vanilla Cookie to induce hallucinations, allowing his group to capture him, though they believed they were only giving Pure Vanilla Cookie a harmless bit of fun. This happens again at the Greater Berry Market when Licorice Cookie uses Poison Mushroom Cookie spores to adulterate a fruit punch, causing reckless and aggressive behavior in almost everyone who drank it. Liquor Cookie is shown to be annoyed with Poison Mushroom Cookie, but it's clear he'll do more for them than for most. Other outliers are Choco Werehound Brute and Bat Cat, who consider him their "boss" and tend to listen to what he says.