MythosLM

Independent reference. Not affiliated with, endorsed by, or sponsored by Anthropic PBC. Details.

What is "Mythos-class"?

What is… informational Last reviewed

A tier, not a single model

"Mythos-class" describes a capability tier, the way "Opus" or "Sonnet" do. Where Opus is Anthropic's broadly-available frontier tier, Mythos-class is the level above it — and, so far, the level with the tightest access controls. Any model Anthropic places in this tier is "Mythos-class."

What's in the tier today

Three releases to date: the April 2026 Preview, and the June 9, 2026 pair Mythos 5 and Fable 5 (same underlying model, different safeguards). Pricing, context and other specs are covered on Claude Mythos specs.

Why the label matters for SEO and accuracy

Before the official name landed, leaks referred to a "Capybara tier." That was a mislabel; the correct, Anthropic-used term is Mythos-class. If a page or post still says "Capybara," it predates or missed the correction — see the rumor, corrected.

Frequently asked questions

Is Mythos-class above Opus?

Yes. Mythos-class is the tier above Opus in Anthropic's lineup.

Which models are Mythos-class?

Mythos Preview, Mythos 5 and Fable 5. All three share the above-Opus tier designation.

Sources & further reading

Facts on this page link to their source. Quotes are kept under 15 words and attributed; figures labelled unofficial are third-party until Anthropic publishes system-card numbers.