Anthropic has launched Claude Fable 5, its most powerful model ever made publicly available. It is the first member of the Mythos class , a new capability tier that sits above Opus , to reach general release. Alongside it, Anthropic also launched Claude Mythos 5, the same underlying model but with safety restrictions lifted, reserved for a small group of vetted cyberdefenders through Project Glasswing.
Mythos-class models are a tier of Claude models that sit above the Opus class in capability. The distinction between the two new models comes down to one thing: safeguards. Fable 5 is the public version with safeguards, while Mythos 5 is the same model with some protections removed, reserved for cybersecurity professionals via Project Glasswing.
Two months in the making
Anthropic first introduced Claude Mythos Preview in April 2026 through Project Glasswing, a restricted program involving partners like AWS, Microsoft, Apple, and CrowdStrike. Anthropic captivated Wall Street and government officials with the unveiling, which excels at identifying security flaws within software. The company said it did not plan to make the model generally available, limiting the rollout to a select group of companies as part of the cybersecurity initiative.
Where Mythos Preview was available to roughly 50 select users, Fable 5 removes that restriction while adding carefully tuned safeguards in high-risk categories. With the launch of Claude Fable 5, Anthropic is honoring its stated "eventual goal" to deploy Mythos-class models at scale.
What makes it different
Fable 5's capabilities exceed those of any model Anthropic has ever made generally available. It is state-of-the-art on nearly all tested benchmarks, showing exceptional performance in software engineering, knowledge work, vision, scientific research, and many other areas. The longer and more complex the task, the larger Fable 5's lead over other models.
The benchmark numbers back that up:
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