Claude Mythos 5.5 spotted in Anthropic's page source; Fable 5.5 briefly appeared in Azure catalog Oct 13
ChrisGPT · x · 2026-11-02
Two unreleased Anthropic models have surfaced publicly:
- Oct 13: LiteLLM's sync bot added azureai/claude-fable-5-5, found in Azure's East US 2 catalog marked "Generally Available", with full cache and input/output token pricing fields.
- Oct 14: The entry was removed after checks found no corresponding Azure listing and returned 404 DeploymentNotFound.
- Oct 31: The author independently verified a 21:49 UTC archived copy of anthropic.com/claude/mythos, where "Claude Claude Mythos 5.5" appears in the hidden page heading and both desktop/mobile image alt texts.
Evidence comes from public GitHub code and Anthropic's own HTML, with the timeline reaching back to Oct 13.
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