Claude Mythos Preview
Claude Mythos Preview was introduced in April 2026 as a general-purpose model with strong cybersecurity capabilities. Anthropic limited its release and used it in Project Glasswing.
Deprecated API; check access details
Why the preview had a limited release
Anthropic’s assessment described vulnerability discovery and exploit-development evaluations. Project Glasswing brought selected organizations into defensive work on critical software. These findings explain the restricted rollout; they do not establish ordinary API access for a new customer.Anthropic assessment of Mythos Preview, April 2026
Current models have separate records
The lifecycle table marks Mythos Preview deprecated. Mythos 5 and 5.1 have distinct identifiers and verification conditions. Partner-operated hosting platforms set their own retirement schedules, so a direct API status should not be applied to every cloud service.Claude model lifecycle and retirement dates
Specifications & access
| Detail | Value and conditions |
|---|---|
| Status | Deprecated API; check access details |
| Access | API |
| Model identifiers | claude-mythos-preview |
| Research announcement | 7 April 2026Anthropic assessment of Mythos Preview, April 2026 |
| Deprecation date | 9 June 2026Claude model lifecycle and retirement dates |
| Retirement date | To be announced on the current lifecycle page.Claude model lifecycle and retirement dates |
| Release scope | Limited defensive-security access; not a general public launch.Anthropic assessment of Mythos Preview, April 2026 |
Related models
- Claude Mythos 5.1
Anthropic · Claude Mythos
Claude Mythos 5.1 gives verified organizations access to the Fable 5.1 model for defensive cybersecurity.
Launch date Restricted accessAPI - Claude Mythos 5
Anthropic · Claude Mythos
Claude Mythos 5 is the verified-access offering of Claude Fable 5 for defensive cybersecurity.
Launch date Restricted accessAPI