The RX-75 Guntank, also known as the RX-75-4 Guntank, is a mobile suit from the Mobile Suit Gundam television series.

The RX-75 Guntank was the first prototype Earth Federation Forces mobile suit developed by Operation V. However, it was said to be closer to a tank rather than a mobile suit. A number of companies such as Takim and Hervic participated in its development. The Guntank had the torso and arms of a mobile suit, but possessed caterpillar treads for legs. Initially, it was designed to be piloted by a crew of two, with a gunner in the canopy-style cockpit on the head and a driver in another cockpit in the torso. However, it was later changed to be controlled by a single pilot in the canopy-style cockpit. Like all "Operation V" mobile suits, the Guntank used the Core Block System.

Its reactor is a hybrid type of nuclear reactors and gas turbines, and its output is insufficient for powering beam weapons. The Guntank's main weapons are twin 120mm cannons, which are effective at long and medium ranges. Its arms have four-barrel missile launchers instead of hands, and they provided good cover fire against enemy tanks and aircraft, but are less effective against enemy mobile suits. A major flaw of the Guntank is its inability to turn its torso, making it difficult to aim the cannons at moving targets, as the Guntank must reposition itself. Another major flaw is that its design was primarily for ground combat, resulting in it having poor maneuverability in space.