In the anime series Gundam SEED, Mirage Colloid a sythetic particle first discovered by the Earth Alliance's Atlantic Federation, which can be used for a variety of military purposes.

The first use discovered was as a stealth device, and this technology was incorporated into the GAT-X207 Blitz Gundam. With the Mirage Colloid system activated, the mobile suit was covered by the particles, which bent light and RADAR waves around it, rendering the Blitz Gundam invisible to both visual and electronic detection. However, the power requirements were substantial, and Mirage Colloid could not be used simultaneously with Phase Shift armor. This application of Mirage Colloid was later incorporated into the MBF-P01-Re<AMATU> Gundam Astray Gold Frame Amatu, which used the severed arm of the Blitz Gundam, and was eventually repeated on a much larger scale to conceal ZAFT's huge superweapon GENESIS, and then on the Earth Alliance battleship Girty Lue.

The next development of Mirage Colloid was the "Geschmeidig Panzer" energy deflection armor, employed by the GAT-X252 Forbidden Gundam and its descendants, the GAT-X255 Forbidden Blue and GAT-706S Deep Forbidden. This system utilized Mirage Colloid particles to bend energy beams away from the mobile suit, providing excellent defensive capabilities. In the amphibious Forbidden Blue and Deep Forbidden units, the "Geschmeidig Panzer" pods were modified to also deflect water, for use as a propulsion system.

While the initial advances in Mirage Colloid technology were made by the Atlantic Federation, a more novel development came from another source: the Mirage Colloid virus streader, created by the defense conglomerate Actaeon Industries and utilized in their prototype NMS-X07PO Gel Finieto. This system used Mirage Colloid particles to access the operating systems of nearby mobile suits and infect them with a computer virus, unimpeded by N-Jammer Canceller interference. However, the Gel Finieto was otherwise unarmed and generally unremarkable, and there was little military interest in the mobile suit.

At the end of the Bloody Valentine War, the Treaty of Junius was signed by representatives of the Earth Alliance and ZAFT. One of its provision banned the use of Mirage Colloid technology, seemingly putting an end to further development of this highly versatile particle. However, a mere two years later, the top secret Earth Alliance battleship Girty Lue used its illegal Mirage Colloid stealth system to launch a sneak attack on ZAFT's Armory One base and steal three prototype Gundam mobile suits. With the treaty seemingly defuct, it's likely that Mirage Colloid research will be renewed in earnest, and even more amazing technologies might be developed from it.