> ## Content Index
> Fetch the complete content index at: https://birchtree.me/llms.txt
> Use this file to discover other available public pages before exploring further.

# Fable 5.1 and Mythos 5.1 are here
- URL: https://birchtree.me/blog/fable-5-1-and-mythos-5-1-are-here/
- Published: 2026-09-01T18:27:24.000Z
- Updated: 2026-09-01T18:27:24.000Z
- Author: Matt Birchler
- Tags: Links

Anthropic: [Introducing Claude Fable 5.1 and Claude Mythos 5.1](https://www.anthropic.com/claude-fable-and-mythos-5-1?ref=birchtree.me)

> Claude Fable 5.1 and Claude Mythos 5.1 are the same model, but with different levels of safeguards.

I think a lot of us believed Fable 5 was the same as Mythos, just with different safeguards, but I don't believe Anthropic ever officially confirmed that. It's good to have the confirmation in this model update.