Expired60% confidenceEventExact time
A user reported that Claude Mythos 5 briefly appeared as a model option in Anthropic's API before being quickly pulled.
2
Sources
60%
Confidence
Medium-term (~90 days)
Relevance
7/2/2026
First Seen
Valid until: 9/30/2026(expired)
Sources
Claude Mythos 5 Allegedly Spotted, Inside OpenAI's Equity Negotiations with the U.S. Government
bilibili黑鸦Heya6/6/2026
Related Claims
UnverifiedClaude Fable 5 and Claude Mythos 5 have officially launched as Anthropic's most advanced AI models to date.72% similarUnverifiedAnthropic's Fable 5 has the internal codename Mythos 5 and is its frontier research-grade model.70% similarUnverifiedAnthropic released two models on September 2nd, Fable 5.1 and Mythos 5.1, which share the same set of base model weights but differ in safety policies and access scope.68% similarUnverifiedClaude Fable is essentially the public version of Claude Mythos 5, with more cybersecurity protection mechanisms built in.67% similarVerifiedAnthropic officially released the first model in the Claude 5 series, named Claude Fable 5.66% similar
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