Anthropic releases its first Mythos-class model Claude Fable
Anthropic just released Claude Fable 5—the first Mythos-class model it deemed too dangerous for public release. Until now.
Why it matters
Anthropic is expanding its model portfolio with a new tier claiming superior performance on complex tasks. The release signals confidence in its safety mechanisms and directly challenges OpenAI and Google's model dominance in reasoning and long-context work.
The key facts
6 to knowClaude Fable 5 is Anthropic's first public Mythos-class model release
Claims 'exceptional performance in software engineering, knowledge work, and vision'
Performance advantage grows on longer, more complex tasks
Mythos class was previously withheld due to cybersecurity capability risks
Release enabled by new safeguards blocking high-risk response categories
Published June 9, 2026
Go to the source
The Verge AItheverge.com
Publisher excerpt: Anthropic just announced Claude Fable 5, a new AI model it said is the most powerful model it has ever made widely available. According to the company, Fable 5 "shows exceptional performance in software engineering, knowledge work, and vision," with its lead over other models growing as tasks…