Silicon Graphics, Inc. (commonly initialised to SGI, historically sometimes referred to as Silicon Graphics Computer Systems or SGCS) was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark. Its initial market was 3D graphics display terminals, but its products, strategies and market positions evolved significantly over time.

Initial systems were based on the Geometry Engine that Clark and Marc Hannah had developed at Stanford University, and were derived from Clark's broader background in computer graphics. The Geometry Engine was the first very-large-scale integration (VLSI) implementation of a geometry pipeline, specialized hardware that accelerated the "inner-loop" geometric computations needed to display three-dimensional images.

SGI was headquartered in Sunnyvale, California; it was originally incorporated as a California corporation in November 1981, and reincorporated as a Delaware corporation in January 1990. On April 1, 2009, SGI filed for Chapter 11 bankruptcy protection and announced that it would sell substantially all of its assets to Rackable Systems, a deal finalized on May 11, 2009, with Rackable assuming the name "Silicon Graphics International". The remains of Silicon Graphics, Inc. became Graphics Properties Holdings, Inc.