The Ultra 1 is a family of Sun Microsystems computer workstations based on the 64-bit UltraSPARC microprocessor. It was the first model in the Sun Ultra series of Sun computers, which succeeded the SPARCstation series. It launched in 1995 and shipped with Solaris 2.5.

The Ultra 1 was available in a variety of different specifications. Three different CPU speeds were available - 143 MHz (Model 140), 167 MHz (Model 170) and 200 MHz (Model 200).

Model numbers with an E suffix (Sun service code A12, internal codename Electron) had two instead of three SBus slots, and added a UPA slot to allow the use of an optional Creator framebuffer. In addition, the E models had Wide SCSI and Fast Ethernet interfaces, in place of the narrow SCSI and 10Base-T Ethernet of the standard Ultra 1 (service code A11, codename Neutron).

Ultra 1 uses 200-pin 5V ECC 60ns DIMM.

Similar Sun machines were the Netra i 1 servers which had the same chassis and the UltraServer 1/Ultra Enterprise 1 servers.