What was the first Xbox console to support 4K Ultra HD Blu-ray discs?

The Xbox One S was the first Xbox console to support 4K Ultra HD Blu-ray discs.

Microsoft announced the Xbox One S at E3 2016 and released it on August 2, 2016. Besides its smaller white design, the console added support for high-dynamic-range video and 4K Ultra HD Blu-ray playback, making it a notable home-entertainment upgrade over the original Xbox One.

The Xbox One S could upscale games to 4K, but it did not render most games natively at 4K. That distinction is important because the later Xbox One X was designed as the more powerful gaming model, with substantially greater graphics performance.

The Xbox One S All-Digital Edition removed the optical disc drive, so it could not play physical 4K Blu-ray discs. The standard Xbox One S, with its disc drive, is the model that introduced this capability to Xbox consoles.