Claude Mythos 5
Claude Mythos 5 Overview
Claude Mythos 5 was the restricted counterpart to Claude Fable 5 — the same underlying model with some safeguards lifted, available only to approved Project Glasswing customers. It was succeeded by Claude Mythos 5.1 on September 1, 2026 and remains available to existing participants as a legacy model.
Superseded: Claude Mythos 5 was succeeded by Claude Mythos 5.1 on September 1, 2026. This page is kept for reference — see the Claude Mythos 5.1 guide for current specs, benchmarks, and pricing.
Access note: Claude Mythos 5 is not a public self-serve model. You cannot sign up for it through the Claude app or standard API billing. Access is limited to approved customers in Anthropic’s Project Glasswing program. For a widely available model with the same underlying capability, see Claude Fable 5.
Claude Mythos 5 (claude-mythos-5) launched alongside Claude Fable 5 on June 9, 2026. The two share the same underlying model; the difference is deployment. Fable 5 ships with safety safeguards that make it suitable for general release. Mythos 5 has some of those safeguards lifted in specific areas, so Anthropic restricts who can use it. This page is an informational overview — it covers what Mythos 5 is, how access works, and how it relates to the rest of the Claude lineup.
ClaudeAIHub. For official information, see Anthropic’s model overview.
How Mythos 5 Relates to Fable 5
Think of Mythos 5 and Fable 5 as two deployments of one model. Fable 5 is the “made safe for general use” version: its classifiers route a small share of high-risk requests (offensive cyber, broad biology/chemistry, distillation attempts) to Claude Opus 4.8. Mythos 5 lifts some of those restrictions for vetted organizations whose legitimate work — such as defensive cybersecurity or biomedical research — requires capabilities the general release deliberately constrains. Specs are the same: 1M token context window, 128k max output, adaptive thinking always on, and listed pricing of $10 input / $50 output per MTok for approved customers.
What Is Project Glasswing?
Project Glasswing is Anthropic’s trusted-access program for deploying less-restricted frontier models to vetted partners. Mythos 5 is deployed initially through a collaboration with the US government, with a planned expansion of trusted access to cybersecurity organizations and biomedical researchers. Mythos 5 succeeds the earlier invitation-only Claude Mythos Preview (claude-mythos-preview), which Anthropic says will be retired after Mythos 5 becomes available to its users.
Who Can Access Claude Mythos 5?
- Not generally available — there is no self-serve sign-up in the Claude app or API console
- Approved Project Glasswing customers — initially government-affiliated cybersecurity and infrastructure partners
- Select biology researchers via the trusted-access program, with planned expansion to more cybersecurity organizations and biomedical researchers
- How to ask: Anthropic directs interested organizations to their Anthropic, AWS, or Google Cloud account team
For everyone else, Claude Fable 5 is the way to use this model generation — generally available via the Claude API and, on a staged basis, through Claude subscription plans. See Claude Models Explained for the full lineup.
Frequently Asked Questions
What is Claude Mythos 5?
Claude Mythos 5 is a restricted-access Anthropic model launched June 9, 2026. It shares the same underlying model as Claude Fable 5 but has some safeguards lifted, so access is limited to approved customers in Anthropic’s Project Glasswing trusted-access program.
Is Claude Mythos 5 available to the public?
No. Claude Mythos 5 is not a public self-serve model. It is offered in limited availability to approved Project Glasswing customers — initially via a US government collaboration, with planned expansion to vetted cybersecurity organizations and biomedical researchers.
Is Mythos 5 the same as Fable 5?
They share the same underlying model. Fable 5 is the widely released version with safety safeguards; Mythos 5 has some safeguards lifted in specific areas and is restricted to trusted-access partners.
What is Project Glasswing?
Project Glasswing is Anthropic’s trusted-access program for deploying less-restricted frontier models to vetted organizations, such as government cybersecurity partners and biomedical researchers. Mythos 5 and the earlier Mythos Preview are deployed through it.
How much does Mythos 5 cost?
Anthropic’s pricing page lists Claude Mythos 5 at per million input tokens and per million output tokens — the same as Claude Fable 5 — for approved customers. There is no public purchase path.
Can I use Mythos 5 in Claude?
No. Mythos 5 does not appear in the Claude app’s model picker and cannot be enabled on Free, Pro, Max, or Team plans. Claude Fable 5 is the generally available model from the same generation.