# Migrating off claude-mythos-5-1

**Anthropic** retires **claude-mythos-5-1** on **2027-09-01** (in 345 days).
No replacement named by the provider.

Source: https://docs.anthropic.com/en/docs/about-claude/model-deprecations
Source last checked: 2026-09-21.
Calendar as of 2026-09-21 UTC.

| Model | Provider | Retires | Replacement |
|---|---|---|---|
| claude-mythos-5-1 | Anthropic | 2027-09-01 | — not named |

Also retiring on 2027-09-01:
- claude-fable-5-1 (Anthropic) → no replacement named

Source: https://llmlatency.dev/migrate/anthropic-claude-mythos-5-1