Goblins
How OpenAI's coding model developed a fantasy creature problem
“There’s probably a little gremlin in your codebase.”[1] “Tiny SourceKit goblin has been escorted from the premises.”[2] “the goblin princess in the datacenter”[3]
Animal imagery started creeping into OpenAI’s GPT‑5.1 with the coding assistant describing bugs, tough situations, edge cases, or anything that refused to behave as expected using goblins and gremlins instead. According to OpenAI’s data, use of “goblin” had risen by 175% in GPT‑5.1 compared to GPT‑5, while “gremlin” had risen by 52%.[4]
The creatures were tracked to an optional “Nerdy” personality setting used during training, designed to sound playful and quirky, which created a loop in coding contexts:
The model learned that answering in a playful style was rewarded because it made answers feel more lively and engaging
Some of those rewarded examples included creature metaphors like goblins and gremlins, which earned higher rewards
The model started using goblins and gremlins more often during training
The outputs were then used to train it further
The use of goblins and gremlins became even more common because the model learned to generalise rewards in certain situations to unrelated ones, even when the Nerdy setting wasn’t being used
OpenAI retired the Nerdy personality and cleaned up the rewards and training data for its next model, but to contain the creatures with GPT‑5.4 OpenAI added a direct instruction to the system prompt for Codex:
“Never talk about goblins, gremlins, raccoons, trolls, ogres, pigeons, or other animals or creatures unless it is absolutely and unambiguously relevant to the user’s query.”Sources:
[1] zetta7re. (2026, April 29). [Comment on reel]. In wutronicai. Where the goblins came from [Video]. Instagram.
[2] Hlbkomer. (2026, April 28). Re: Why does GPT 5.5 have a restraining order against goblins? [Comment]. r/ChatGPT. Reddit. https://www.reddit.com/r/ChatGPT/comments/1sxwmis/why_does_gpt_55_have_a_restraining_order_against/
[3] pierukainen. (2026, April 28). Re: Why does GPT 5.5 have a restraining order against goblins? [Comment]. r/ChatGPT. Reddit. https://www.reddit.com/r/ChatGPT/comments/1sxwmis/comment/oipxfxg/
[4] OpenAI. (2026, April 29). Where the goblins came from. https://openai.com/index/where-the-goblins-came-from/