|Country of origin||United States|
|Precision||Fire control quality three-dimensional data|
The AN/SPG-55 was an American tracking / illumination radar for Terrier and RIM-67 Standard missiles (SM-1ER/SM-2ER). It was used for target tracking and surface-to-air missile guidance as part of the Mk 76 missile fire control system. It was controlled by a UNIVAC 1218 computer.
- First letter (installation) - S = Water (surface ship)
- Second letter (type of equipment) - P = Radar
- Third letter (purpose) - G = Fire Control or Searchlight Directing
AN/SPG-55 was fitted on numerous ships in the United States Navy including Kitty Hawk-class aircraft carriers, Belknap and Leahy-class cruisers and Farragut class destroyers. It was also used on the nuclear-powered single units Long Beach, Bainbridge and Truxtun. The Italian Navy used it aboard the cruisers Andrea Doria, Caio Duilio, Giuseppe Garibaldi and Vittorio Veneto.
- AN/SPG 55 - Original version supported Beam riding Terrier missiles.
- AN/SPG 55A - Supported Beam-riding and homing Terrier missiles
- AN/SPG 55B - Supported Beam-riding and homing Terrier missiles as well as newer Standard missiles.