The Nikon D3X is a 24.4-megapixel professional-grade full-frame digital single-lens reflex camera (DSLR) announced by the Nikon Corporation on 1 December 2008. The D3X is the third camera in Nikon's line to offer a full-frame sensor, following the D3 and D700. As Nikon's new flagship model, it augments the Nikon D3S, Nikon's high-speed professional model, and while the D3S retains advantages in terms of high ISO performance and higher frame rate, the D3X offers a dramatic increase in resolution and image detail.

Nikon Corporation is a Japanese optics and photographic equipment manufacturer headquartered in Tokyo, Japan. The companies held by Nikon form the Nikon Group.