LLM Countdowns / Anthropic / Claude Fable 5.5
Anthropic
Claude Fable 5.5
Tracked as: Claude Fable 5.5 / Mythos 5.5
Estimated release
Nov 5, 2026
Early Nov 2026
Details
- Status
- Opus 5.5, Sonnet 5.5 and Haiku 5.5 are out; Fable is the missing tier
- Current model
- Claude Fable 5.1, 53.4 on the Intelligence Index, released Sep 1, 2026 ()
- Projected score
- About 60.4 (+7)
- Typical cycle
- About 60 days between releases
Why this date
- Opus 5.5 (Sept 22, 57.6) and Sonnet 5.5 (Sept 28, 56) both already outscore Fable 5.1 (53.4); Haiku 5.5 shipped Oct 7, leaving Fable 5.5 as the missing top tier of the Claude 5.5 family
- Would keep the Fable 5.1 pattern: one model with two safeguard tiers, generally available Fable plus Mythos behind trusted access
- GPT-6.1 Sol (51.8, Sept 29) now sits under two points behind Fable 5.1 at a far lower price, so the pressure is on cost per task as well as score
- Fable 5.1 cut cache-read prices 75% but still cost about 20% more per task than Fable 5; expect another round of efficiency work
Source: Anthropic Fable 5.1 / Mythos 5.1 launch (Sept 1, 2026), Claude Opus 5.5 launch (Sept 22, 2026), Claude Haiku 5.5 launch (Oct 7, 2026; https://www.anthropic.com/claude/haiku) & Artificial Analysis Index v4.3.2
More from Anthropic
November 2026
- Nov 5 Claude Fable 5.5
December 2026
- Dec 8 Claude Opus 5.6
- Dec 15 Claude Sonnet 5.6