ModelAnthropic · Joined Apr 7, 2026 · Claude Mythos

Claude Mythos Preview

Model at Anthropic

Claude Mythos Preview does not have a researched profile yet. Everything here comes from its recorded changes and public listings, each linked to its source.

The basics

As of Nov 1

Status: Available

Updates

Jun 9

Retiring

Claude Mythos Preview deprecated, retirement date to be announced

The model deprecations table lists claude-mythos-preview as deprecated on June 9, 2026, the day Mythos 5 launched as its upgrade. No retirement date has been set.

Apr 7

New release

Claude Mythos Preview opens as a gated research preview

Anthropic made Claude Mythos Preview available as an invitation-only research preview for defensive cybersecurity work through Project Glasswing.

Full changelog, by month

Role

Restricted frontier model at Anthropic

Claude Mythos 5.1Sep 2026 to now · 2 months
Claude Mythos 5Jun 2026 to Sep 2026 · 3 months
Claude Mythos Preview
Apr 2026 to Jun 2026 · 2 months

Similar models

Claude Mythos 5

Model

Claude Mythos 5.1

$10 in, $50 out

Similar models for now. Real viewing data comes after launch.

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