What was the original name of the Xbox Series X console during development?

The Xbox Series X was developed under the name Project Scarlett.

Project Scarlett was Microsoft's development codename for the next-generation Xbox family announced at E3 2019. The final hardware lineup became the Xbox Series X and Xbox Series S, both released in November 2020.

The Series X was designed as Microsoft's high-performance console, featuring a custom AMD processor, solid-state storage and support for high-resolution gaming. Microsoft revealed the final name and the distinctive tower-like design at The Game Awards in December 2019.

Project Scorpio is a different codename: it referred to the Xbox One X, the upgraded Xbox One released in 2017. Durango was associated with the Xbox One during its development, while Project Natal was the development name for Kinect. These codenames belong to different generations and accessories.