Why did ChatGPT become obsessed with goblins and gremlins?

ChatGPT recently became so obsessed with mentioning goblins and gremlins in its responses that its creator, OpenAI, had to issue a system prompt instructing the bot to avoid mention of such creatures. It all started in November when GPT-5.1 was released with the option to give ChatGPT a personality when users interacted with it. One of the options was “nerdy,” and that personality decided it needed to use words like “goblin” as much as possible.

An investigation revealed that ChatGPT’s use of the word “goblin” increased by 175 percent following the November rollout. At the same time, use of “gremlin” jumped 52 percent. Those numbers continued to climb after GPT-5.4 was released in March. OpenAI found the culprit after mapping the use of “goblin” across the bot’s different personalities. The nerdy version was responsible for 66.7 percent of all “goblin” uses, despite only accounting for 2.5 percent of all ChatGPT responses. That personality is no longer an option, and GPT-5.5 has been expressly ordered to “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.”