The Nikon D850 is a professional-grade full-frame digital single-lens reflex camera (DSLR) produced by Nikon. The camera was officially announced on July 25, 2017, launched on August 24, 2017, and first shipped on September 8, 2017. Nikon announced it could not fill the preorders on August 28, 2017 and filled less than 10% of preorders on the first shipping day. It is the successor to the Nikon D810.

A full-frame DSLR is a digital single-lens reflex camera (DSLR) with a 35 mm image sensor format. Historically, 35 mm was one of the standard film formats, alongside larger ones, such as medium format and large format. The full-frame DSLR is in contrast to full-frame mirrorless interchangeable-lens cameras, and DSLR and mirrorless cameras with smaller sensors, much smaller than a full 35 mm frame. Many digital cameras, both compact and SLR models, use a smaller-than-35 mm frame as it is easier and cheaper to manufacture imaging sensors at a smaller size. Historically, the earliest digital SLR models, such as the Nikon NASA F4 or Kodak DCS 100, also used a smaller sensor.