MS-05 Zaku I

In the Mobile Suit Gundam universe, the MS-05 Zaku I (ザクI, Zaku Wan?) was the first successful mobile suit design to be developed by the Zeonic Company in the Principality of Zeon's quest to develop a combat-capable mobile suit that used the AMBAC System and the Minovsky ultracompact fusion reactor. The Zaku I was first designed and built in U.C. 0075, winning over the EMS-04 Zudah (later renumbered the EMS-10 Zudah in Mobile Suit Gundam MS IGLOO) in a special competition to decide Zeon's first-ever active-service mobile suit. It was put into mass-production later that year as the MS-05B Zaku I. The last production run of the MS-05B is in U.C. 0077, before it was replaced by the newer MS-06 Zaku II.

The MS-05A Zaku I was the first attempt made by the Principality of Zeon. It was also the first mobile suit to use the Minovsky-lonesco fusion reactor and mimic human movements. During November 0075, 27 of these units were assigned to new pilots for evaluation. Among them were Ramba Ral, the "Blue Giant," and the Black Tri-Stars Gaia, Mash, and Ortega. The feedback from the pilots helped engineers in their development of the MS-05B, which was different from the A model with its redesigned cockpit, higher-output power plant, and redesigned armor.

The MS-05A was not mass-produced as intended, labeled unfit for combat before the start of the One Year War. Still, the success of these suits prompted the Zeon Navy to commission ships that could carry them into combat, primarily the Musai-Class Light Cruiser. The service entry of the Zaku II relegated all Zaku Is for rear-guard use as supply and construction suits, although they would be used for colony-gassing operations in the early stages of the war. Later, with the number of machines lost after Operation British and the Battle of Loum, many of these machines were brought back to the front lines until losses could be replaced. Many units were assigned to the Midnight Fenrir Corps on the eve of the Second Earth Descent Operation. The MS-05A would continue to serve as patrol units and workers until the end of the war.