The RX-139 Hambrabi is a prototype transformable mobile suit featured in the Mobile Suit Zeta Gundam anime series.

During the Gryps Conflict, the Earth Federation Forces and the Titans developed several experimental transformable mobile suits/mobile armors and conducted field tests by placing them into actual combat. One of the more well-known designs was the RX-139 Hambrabi, and it was unique in several respects. Developed with the help of Paptimus Scirocco, the Hambrabi featured a simplified transformation system to make it more suitable for mass production.

One of the most visibly unique features were the five mono-eye sensors placed all over its body, enabling the pilot to more easily locate and track targets in both mobile suit and mobile armor modes. Although its generator and thruster output were nothing special, the Hambrabi could engage in high-speed combat for a longer period due to more efficient combustion of its propellant. It was also very maneuverable, and one of the few transforming mobile suits to retain its close combat capabilities even in mobile armor mode, allowing it to use its handheld weapons and forearm-mounted claws regardless of its form.

Besides the forearm-mounted claws, the Hambrabi was also armed with a pair of beam rifles, a pair of beam sabers, a tail lance, and can use the RX-110 Gabthley's Fedayeen rifle, as well as the "sea serpent," a wired grappling weapon used to deliver crippling electrical shocks to enemy mobile suits. Despite having excellent production costs and ease of maintenance, only a few Hambrabi units were built as it was discovered that to utilize the machine effectively, its pilot must be highly skilled and have a unique 'combat sense'.