The GAT-X102 Duel Gundam is a mobile suit introduced in the anime Mobile Suit Gundam SEED. It was piloted by Yzak Joule.

The Duel Gundam is the first unit to be developed in the Earth Alliance's G Project series of prototype MS. Equipped with the new Phase Shift armor that makes it nearly impervious to most physical weapons, the Duel is designed as a general-purpose machine that has well-balanced performance, and also serves as a development base for the other MS in the project.

The Duel's armament consists of two head-mounted "Igelstellung" 75mm multi-barrel CIWS guns, which later become standard weaponry on most Earth Alliance's suits to intercept incoming missiles and closing in enemy units, two beam sabers stored on the backpack and hand-carried for use in close combat, a 57mm High-energy Beam Rifle with an attached 175mm grenade launcher for ranged combat, and an anti-beam coated shield for defense. Duel also has a Rail Bazooka as an optional weapon, but it was taken and used by MBF-P01 Gundam Astray Gold Frame to escape from Heliopolis.

After being stolen by ZAFT and damaged in battle with the GAT-X105+AQM/E-X01 Aile Strike Gundam, the suit is upgraded with the Assault Shroud. The Assault Shroud is a set of ejectable armor mounted on the Duel’s body to enhance overall combat performance. It adds a "Shiva" 115mm railgun to the right shoulder and a 220mm 5-barrel missile pod to the left shoulder for additional firepower, as well as various leg and backpack-mounted thrusters for better mobility. Although the equipment worked well in space, it performs poorly under gravity due to its bulk.