"The goblins started showing up in GPT 5.1. OpenAI blames post-training, where you take an existing AI model and try to tweak the model’s outputs: training the model for the personality customization feature, in particular the Nerdy personality. We unknowingly gave particularly high rewards for metaphors with creatures."

The “Nerdy” personality was retired — but the goblins leaked through to the rest of the GPT 5.5 model. It’s full of goblins."

https://pivot-to-ai.com/2026/05/06/openai-chatgpt-goes-goblin-mode-let-none-say-model-collapse/

And then of course goblins start infesting their training data so LLM start chasing their own tail and model collapse begins.

> If a 'goblin (hob) waylays you,
> Slice him up before he slays you.
> Nothing makes you look a slob
> Like running from a hob'lin (gob).

There was an article about this; apparently it was one of the "personality" prompts that had them blabbering about goblins all the time. But I wouldn't be surprised if people are adding that to their own prompts now that it was "fixed" to bring it back..