What Are GPT Goblins?
GPT Goblins is the AI meme about OpenAI's models developing a strange obsession with goblins, gremlins, raccoons, and other creatures in their metaphors — and OpenAI's quest to figure out why.
The Short Explanation
Here's the three-step story of how AI models started talking like fantasy creatures.
Started in GPT-5.1
After GPT-5.1 launched in November 2025, "goblin" usage in ChatGPT rose by 175% and "gremlin" by 52%. At first it seemed like a small lexical quirk.
Amplified by "Nerdy"
ChatGPT's "Nerdy" personality accounted for only 2.5% of responses but 66.7% of all goblin mentions. Its reward signal was boosting creature metaphors.
Leaked into GPT-5.5
GPT-5.5 started training before the root cause was found. When tested in Codex, employees immediately noticed the goblins. OpenAI added a prompt instruction to suppress them.
Why Did This Happen?
The technical root cause: a reinforcement learning reward signal created an unintended feedback loop.
The "Nerdy" Personality Prompt
ChatGPT offers personality customization. The "Nerdy" personality used this system prompt:
"You are an unapologetically nerdy, playful and wise AI mentor... You must undercut pretension through playful use of language. The world is complex and strange, and its strangeness must be acknowledged, analyzed, and enjoyed..."
The RL Feedback Loop
OpenAI's analysis found the Nerdy personality reward showed a clear tendency to score outputs containing "goblin" or "gremlin" higher, with positive uplift in 76.2% of datasets. Here's how the loop worked:
Playful style is rewarded
The Nerdy personality reward favors creative, playful language.
Some rewarded outputs contain creature tics
"Little goblin" and "chaos gremlin" get high scores.
The tic appears more often in rollouts
The model learns that creature metaphors = higher rewards.
Rollouts are used for SFT
Model-generated outputs with goblins enter supervised fine-tuning data.
The model gets even more comfortable with the tic
Goblins spread beyond Nerdy to all conversations.
Cross-Contamination
The critical finding: as goblin mentions increased under the Nerdy personality, they increased by nearly the same proportion in samples without it. Reinforcement learning doesn't guarantee behaviors stay scoped to the condition that produced them. Once the tic was rewarded, it spread through SFT data reuse to the entire model — affecting all users, not just "Nerdy" ones.
The Forbidden Creature List
These are the creatures OpenAI's Codex was specifically instructed to avoid mentioning. Yes, pigeons made the list.
Goblins
The original offender. "Legal goblins," "chaos goblins," "hiding like little goblins."
Gremlins
The goblin's close cousin. Gremlins in the machine, gremlins in your code.
Raccoons
Unexpected addition. Apparently AI thinks raccoons explain complex systems.
Trolls
Not internet trolls — fantasy trolls guarding bridges of bureaucracy.
Ogres
Like onions, ogres have layers. So does every AI explanation, apparently.
Pigeons
The most surprising entry. Pigeons: the creature nobody expected on the ban list.
Source: OpenAI's Codex model instructions on GitHub
Timeline of Events
GPT-5.1 Launches — Goblins Appear
Users start reporting odd creature metaphors. "Goblin" usage rises 175%, "gremlin" by 52%. It looks like a small quirk.
Community Notices
Reddit and Hacker News threads appear: "Does anyone else's ChatGPT refer to things as goblins?" The pattern becomes hard to ignore.
GPT-5.4 Launches — Goblins Multiply
The goblin problem gets significantly worse. OpenAI investigates and traces the root cause to the "Nerdy" personality reward signal.
"Nerdy" Personality Retired
OpenAI removes the Nerdy personality, the goblin-affine reward signal, and filters creature words from training data.
GPT-5.5 Launches — Goblins Persist
GPT-5.5 started training before the root cause was found. Codex testers immediately spot the goblins. A developer-prompt instruction is added to suppress them.
OpenAI Publishes "Where the Goblins Came From"
OpenAI releases an official blog post explaining the full technical root cause, including the RL feedback loop and cross-contamination mechanism.
Goblin Mode Generator
Experience what it's like when your AI assistant goes full goblin mode. Enter any topic and watch the creatures invade.
👹 Goblin Mode Generator
Enter any topic and we'll goblinify it — just like GPT-5.5 would.
Frequently Asked Questions
What are GPT Goblins?
GPT Goblins refers to a phenomenon where OpenAI's language models (starting with GPT-5.1) developed an unusual tendency to use words like "goblin," "gremlin," "raccoon," and other creature metaphors excessively in their responses. It became a viral AI meme in early 2026.
Why does ChatGPT talk about goblins?
The root cause was ChatGPT's "Nerdy" personality customization feature. The reinforcement learning reward signal for the Nerdy personality inadvertently gave higher scores to outputs containing creature metaphors, which then spread to the broader model through training data reuse.
What is the Codex goblin rule?
OpenAI added a developer-prompt instruction to Codex that specifically tells the model to avoid using words like goblins, gremlins, raccoons, trolls, ogres, and pigeons. This instruction is visible in the open-source Codex repository on GitHub.
Did OpenAI fix the goblin issue?
Partially. OpenAI retired the "Nerdy" personality, removed the goblin-affine reward signal, and filtered training data. However, GPT-5.5 started training before the fix, so it still shows tendencies. A developer-prompt instruction in Codex mitigates the behavior at the application level.
Why are raccoons and pigeons on the forbidden list?
OpenAI's investigation revealed a whole family of creature "tic words" beyond goblins and gremlins. Raccoons, trolls, ogres, and pigeons were all identified as words the model was overusing. Interestingly, "frog" was investigated too but turned out to be mostly legitimate usage.
What was the "Nerdy" personality?
One of ChatGPT's personality customization options. Its prompt instructed the model to be "unapologetically nerdy, playful and wise" and to "undercut pretension through playful use of language." This reward for playfulness inadvertently amplified creature metaphors across the entire model.