The MS-06 Zaku II was a series of mobile suits produced and operated by the Principality of Zeon. It was Zeon's primary mass production mobile suit series throughout the One Year War. 

Following the success of the MS-05 Zaku I, Zeon's first combat mobile suit, the Zeon military leadership ordered Zeonic to continue its development. In response, Zeonic developed a new mobile suit based on the design of the MS-05. The prototype for this mobile suit rolled out in August, U.C. 0077. Originally intended as an improved model of the MS-05, this prototype was instead given the new model number of MS-06A due to its signficantly different appearance and vastly improved performance, marking the birth of the MS-06 Zaku II.