Anthropic Launches Claude Fable 5: First Public Mythos-Class Model Now Available

On June 9, Anthropic officially launched Claude Fable 5, its first Mythos-class model available to the public. According to the company, this model demonstrates "exceptional performance" across software engineering, knowledge work, visual recognition, and scientific research, with overall capabilities surpassing all previously released models. Anthropic emphasizes that Fable 5 has passed safety assessments and can be safely deployed in general-purpose scenarios.

Alongside this release, Anthropic also introduced the more powerful Mythos 5 model, which claims to offer the world's strongest cybersecurity capabilities. Mythos 5 is deployed through Project Glasswing as an upgrade to Claude Mythos Preview. Currently, this model is only available to users who already have access to Mythos Preview, including Apple. Anthropic says it will gradually expand Mythos 5's availability through a broader trusted access program. Notably, most queries related to cybersecurity, chemistry, and biology will be handled by the Opus 4.8 model, not Fable 5.

This release also includes the launch of Claude Opus 4.8. During the WWDC 2026 keynote, Apple briefly showed a slide listing numerous new features across iOS 27, macOS 27, watchOS 27, and other systems, involving deep integration with Anthropic models. The rollout of Fable 5 marks Anthropic's key achievement in balancing safety with high performance, while the targeted release of Mythos 5 signals a new phase in enterprise-grade AI security applications.