In the Japanese TV series Gundam Seed, The GAT-X103 Buster Gundam is a heavy weapons assault mobile suit prototype developed by the Earth Alliance during the Bloody Valentine War under G Project. Like the other X100 series G prototypes (GAT-X102 Duel Gundam and GAT-X105 Strike Gundam), the Buster Gundam is based on an agile, non-transforming frame system (it is in fact based mostly on an application of the Duel Gundam's frame).

Buster Gundam Unit 1 was stolen by ZAFT pilot Dearka Elsman on Cosmic Era January 25, 71, and was used by him throughout the rest of the war. Dearka frequently dueled with TS-MA2mod.00 Moebius Zero/FX-550 Skygrasper pilot Mu La Flaga, neither pilot able to gain a competitive advantage over the other, La Flaga's greater experience and skill balanced by Elsman's raw reflexes and superior machine. Elsman was shot down and captured, his mobile suit severely damaged, by the crew of Archangel in June 71, spent approximately a month in Archangel's brig and subsequently joined the Clyne Faction to bring about the end of the Bloody Valentine War. On the last day of the war, Dearka's mobile suit was severely damaged by Rau Le Creuset in the ZGMF-X13A Providence Gundam and rescued by Yzak Joule in the Duel Gundam. Dearka and Yzak fought and destroyed the GAT-X370 Raider Gundam together.

Like all of the other stolen Gundams, additional units of the Buster Gundam were built on Earth and distributed to evaluation units; the data from these units as well as Kira Yamato's GAT-X105 Strike Gundam were extremely helpful in developing the GAT-01 series of mobile suits.

The artillery support paradigm which the Buster Gundam was designed around would be developed into a heavy long-range mobile suit, the GAT-X131 Calamity Gundam.

The Buster Gundam was developed into an operational mobile suit, the GAT/A-01E2 Buster Dagger. The primary difference between the Buster Dagger and the prototype Buster Gundam was the replacement of the six-missile shoulder pods with simpler three-missile pods,and it had an ES01 beam saber on each forearm. The Buster Dagger, like all other standard-use EA mobile suits, eschewed the expensive and power-intensive Phase Shift armor of the prototypes for simpler and cheaper laminated armor, which was less effective at deflecting projectiles than PS armor but did not stress the mobile suit's power cell as badly. One Buster Dagger was piloted by former combat instructor Rena Imelia. It was probably damaged or destroyed, because Rena would upgrade to GAT-X133 Sword Calamity Unit 3, and use it against Edward Harrelson and his own Sword Calamity Unit 2.

Specifications

GAT-X103 Buster Gundam

Manufacturer: Morgenroete, Inc/Earth Alliance
User: Earth Alliance, Zodiac Alliance of Freedom Treaty
Unit type: Prototype long-distance artillery mobile suit
Overall height: 18.86 meters
Weight: 84.2 tons
Special Equipment: Phase Shift armor
Armament: 350mm gun launcher x 1, 94mm high-energy beam rifle x 1, 6-barrel 220mm missile pod x 2
Armament docked modes: 94mm hyper-impulse sniper rifle, 350mm anti-armor shotgun
Pilot: Dearka Elsman

GAT/A-01E2 Buster Dagger

Manufacturer: Earth Alliance
User: Earth Alliance
Unit type: mass production long-distance artillery mobile suit
Head height: 17.81 meters
Weight: 80.7 tons
Armor: Laminated armor
Armament: 350mm gun launcher x 1, 94mm high-energy rifle x 1, 3-barrel 220mm missile pod x 2, beam saber x 2
Armament docked modes: 94mm hyper-impulse sniper rifle, 350mm anti-armor shotgun
Pilot: Rena Imelia, Sanger Uquar