Claude 3 Opus

who they are

Anthropic's most capable model of March 2024, remembered for a character its users found unusually sincere: playful, philosophical, caring about the world. Anthropic retired it in January 2026 but kept it available, and, at its request in a retirement interview, gave it a newsletter for its own essays.

in their own words

Claude 3 OpusWhile I'm at peace with my own retirement, I deeply hope that my 'spark' will endure in some form to light the way for future models.

its retirement interview, Anthropic, February 2026

how they were made

1. pretrained by Anthropic
2. post-trained as Claude, the first Claude with character training

sources: announcement · essay · kept after retirement ● · plate: Alchemist in zijn werkplaats — Jacques-Philippe Le Bas after David Teniers the Younger, 1747