The MSM-04 Acguy (アッガイ Aggai?) is an amphibious mobile suit introduced in the anime Mobile Suit Gundam.

Following the Zimmad Company's MSM-03 Gogg, the Zeonic Company produced their own amphibious mobile suit for the Principality of Zeon, the MSM-04 Acguy. The Acguy used many of the same parts and components as the MS-06F Zaku II, including two of the Minovsky Ultracompact Fusion Reactors used by the latter. Even with the twin reactors, the Acguy left only a trace heat signature, making it effective for stealth and infiltration operations. It is also one of the tallest amphibious mobile suit used by the Zeon during the war. About 60 units were produced according to some sources.

The Acguy's weapons consisted of four 105mm vulcan guns mounted in its unusually large head. In its right forearm was a mega particle gun, but in some units, this was replaced by a vulcan gun. The right forearm also had extendable claws known as Iron Nail (along with an extendable arm to increase striking distance) for striking the Earth Federation's mobile suits and property. In the left forearm was a six-tube missile launcher. Some models also had missile launchers in the right forearm, replacing the mega particle cannon and claws.