Anthropic's own Mythos page already says Claude Mythos 5.5

Anthropic's own Mythos page now names Claude Mythos 5.5. The page header and the wordmark's alt text at anthropic.com/claude/mythos read "Claude Mythos 5.5", while everything below it, including availability and pricing, still describes Mythos 5.1. We read the page source directly on November 1 at about 15:30 UTC. Anthropic has not announced the model.

WHAT IS SOURCED

- The string "Claude Mythos 5.5" appears six times in the page's HTML, all in the header and wordmark. - The announcements list on the same page still ends at October 6 (the Cyber Verification Program expansion), and its newest model entry is Mythos 5.1 from September 1. - Anthropic's Fable, Opus, Sonnet and Haiku pages show no new version numbers when we checked them at the same time. - No Mythos 5.5 id is on OpenRouter or models.dev. - @kimmonismus flagged the page source first, on a tip from @SergioOSINT.

WHAT WE DO NOT KNOW

When Mythos 5.5 ships, what it costs, and whether access widens beyond vetted organizations, as with Mythos 5.1. A page header updated early is a strong sign of a coming release, not a release. Whether Fable 5.5 ships with it, as Fable 5.1 shipped with Mythos 5.1 on September 1, is also unknown.

Mythos 5.5 is now armed on our radar. The alert fires when it answers on a public API.