Claude Mythos 5 is 📝Anthropic's Mythos-class frontier model released June 9, 2026 — the same underlying model as 📝Claude Fable 5, with safety guardrails lifted in some domains for trusted partners.
Claude Mythos 5 is the less-restricted member of Anthropic's Mythos-class family. It shares Fable 5's underlying model and $10 / $50 per-million-token pricing, but lifts Fable 5's automatic routing of high-risk queries — selectively restoring capability in areas like cybersecurity that the public model defers to 📝Claude Opus 4.8. Anthropic deploys it first to trusted cyber-defense partners, with a planned biology-focused trusted-access program that keeps cybersecurity safeguards in place.
Mythos 5 descends from 📝Claude Mythos Preview, the unreleased research model Anthropic considered too capable for public release and used to power its Project Glasswing security initiative. Anthropic states Mythos 5 delivers comparable or stronger performance than the Preview at less than half the cost. Together, Fable 5 and Mythos 5 are Anthropic's first Mythos-class models to reach users beyond the Preview's restricted cohort.