Anthropic released two models on June 9, 2026, and called them both part of the same family — but they are not the same product, they are not available to the same people, and they are not appropriate for the same use cases. Claude Fable 5 is the most capable AI model Anthropic has ever made publicly available. Claude Mythos 5 is the same underlying model with its most sensitive capabilities unlocked, available exclusively to vetted cybersecurity organizations through a controlled access program. If you are trying to figure out which one matters to you, what the benchmarks actually mean, what the pricing commits you to, and what the safety architecture separating the two models really does — this guide covers everything that has been confirmed as of June 11, 2026.
Key Takeaways
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Claude Fable 5 and Claude Mythos 5 share identical model weights — the difference between them is entirely in what each model is permitted to do, enforced through safety classifiers that Fable 5 applies and Mythos 5 has lifted in specific high-risk domains.
Fable 5 is the first publicly available Mythos-class model — released June 9, 2026, available via the Claude API (claude-fable-5), Claude apps, and Amazon Bedrock, and included free for Pro, Max, Team, and Enterprise subscribers through June 22, 2026.
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Mythos 5 is not a general release — it is the upgrade to Claude Mythos Preview within Project Glasswing, available initially only to vetted cyber defenders, infrastructure providers, and select life sciences organizations in collaboration with the US government.
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Both models are priced at $10/$50 per million input/output tokens — exactly double the rate of Claude Opus 4.8, and less than half the price of Claude Mythos Preview (previously $25/$125 per million tokens).
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Fable 5 leads all publicly available models on agentic coding benchmarks: 80.3% on SWE-Bench Pro versus 69.2% for Opus 4.8, 58.6% for GPT-5.5, and 54.2% for Gemini 3.1 Pro.
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Mythos 5's unrestricted cybersecurity capabilities represent a dual-use risk that Anthropic explicitly acknowledged — the model can autonomously construct multi-step exploit chains, which is why access is restricted to Project Glasswing partners working on defensive security for critical infrastructure.
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The safety reroute in Fable 5 triggers in under 5% of sessions on average — queries that exceed the safety threshold fall back to Claude Opus 4.8, with the handoff happening in under seconds and transparently noted to the user.
What Are Claude Fable 5 and Claude Mythos 5?
Claude Fable 5 and Claude Mythos 5 are Anthropic's fifth-generation frontier models, representing the first public release of what Anthropic internally calls the "Mythos-class" tier — a capability level that exceeds everything Anthropic has previously made generally available, launched simultaneously on June 9, 2026, as two distinct products with different access policies and safety configurations.
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