Sun Microsystems, Inc. (NASDAQ: SUNW) is a vendor of computers, computer components, software, and information-technology services, founded in 1982 and headquartered in Santa Clara, California, in Silicon Valley. Sun's manufacturing facilities are located in Hillsboro, Oregon and Linlithgow, Scotland.

Sun's products include computer servers and workstations based on its own SPARC and AMD's Opteron processors, the Solaris operating system, the NFS network file system, and the Java platform. From June 2005, Sun also produces laptops called Ultra 3 Mobile Workstation. The pioneering OpenLook (Sun's own graphical user interface) was very stable but would now be considered minimalistic. A wide choice of windowing systems are now offered, including Open source contributions.

Sun Microsystems is headquartered on the west campus of Agnews Developmental Area in Santa Clara, California, which was formerly an asylum.