Anthropic
LLMsReleased
Anthropic's Claude model line. Fable 5.1 is the current generally available flagship, with Mythos 5.1 limited to trusted-access programs.
Claude Fable 5.1
ReleasedSeptember 1, 2026
Sources
Introducing Claude Fable 5.1 and Claude Mythos 5.1 ↗
Anthropic introduced Fable 5.1 and Mythos 5.1 in September 2026 as its most advanced models for coding, knowledge work, and research.
As of 2026-09
Claude Platform release notes ↗
The Claude Platform lists the Fable 5.1 and Mythos 5.1 launch on September 1, 2026.
As of 2026-09
Timeline
Claude Fable 5
June 9, 2026
Claude Fable 5.1
September 1, 2026