What is Claude Mythos 5?

The unrestricted edition

Mythos 5 is what you get when you take the June 2026 Mythos-class model and remove Fable 5's classifier layer. There is no rerouting to Opus 4.8 in covered domains — the full model answers directly. Because that removes a safety control, Mythos 5 is not offered publicly: it is Glasswing-only, available to the small set of vetted organisations in the program.

Same brains, different guardrails

The intelligence of Mythos 5 and Fable 5 is identical — they are the same weights. What differs is governance: Fable 5 is the safeguarded, public edition; Mythos 5 is the unsafeguarded, restricted edition. See the side-by-side on Fable 5 vs Mythos 5.

Specs

Mythos 5 shares the generation's specs — 1M context, up to 128k output, Covered Model status, 30-day retention, no ZDR. Reference pricing is $10/$50 per million tokens. See Claude Mythos specs.

Status

Mythos 5 access is suspended under the same export-control directive that paused Fable 5. See Is Claude Mythos available?.