Claude Mythos 5
Hall of Fame—
Known for
Vetted cyberdefence and biology work on the Fable 5 generation.
Claude Fable 5 with the safety classifiers lifted, offered to Project Glasswing partners from June 2026 and superseded by Mythos 5.1 in September. The model behind the top SWE-bench Pro and Terminal-Bench 2.1 scores in Anthropic's own Fable 5 card.
What it does8
- Same capabilities as Fable 5, without the classifiers that decline a request
- Glasswing partners first, with cyber safeguards lifted; select biology researchers next
- Access through an Anthropic, AWS or Google Cloud account team
- 1M-token context, 128K output
- Adaptive thinking always on
- $10 / $50, with no Priority Tier
- Thirty-day data retention required
- Superseded by Mythos 5.1 on 1 September 2026
From Claude Mythos 5’s own site. Not used for ranking.
Industry leader
Invite only, through Project Glasswing. Listed for context, not placed.
Compared with everyone else on this board.