Anthropic releases Claude Fable 5, its first generally-available Mythos-class model

Anthropic released Claude Fable 5 on June 9, 2026 — the first generally-available model in a new “Mythos” class that the company positions above its Opus tier in capability. Anthropic reports state-of-the-art results on nearly all tested capability benchmarks, with particular strength in software engineering, knowledge work, vision, and scientific research, and says Fable 5 and the restricted Mythos 5 can work autonomously for longer than any prior Claude.

The shape of the release is the part to watch. Fable 5 is the public, safety-gated counterpart to Claude Mythos 5 (claude-mythos-5), an unrestricted variant released only to a small set of cyberdefenders and infrastructure providers; on some sensitive topics Fable 5 hands the response to Claude Opus 4.8 instead, tuned to trigger in under 5% of sessions on average. A capped public model paired with an uncapped defender-only model is a new pattern for a frontier launch, and it lands days after Anthropic’s own warning that AI capability is outrunning safety assurances.

Pricing is $10 / $50 per million input / output tokens — double the Opus 4.8 list rate. On this site, Fable 5 is now the top row of the Claude lineage and the current Claude entry on the frontier-models roster; Opus 4.8 (May 28, 2026) stays the flagship of the everyday Opus tier. It is also the model Anthropic had been describing, in the Opus 4.8 release notes, as the “bridge” to Mythos-class capability.