|ZGMF-X666S Legend Gundam|
|Prototype attack mobile suit|
|Known Pilot||Rey Za Burrel|
|Overall Height||18.86 meters|
|Weight||86.02 metric tons|
|Power Plant||Ultracompact hyper deuterion nuclear reactor, power output rating unknown|
|Accommodation||Pilot only, cockpit in chest|
|Special Equipments and Features|
The ZGMF-X666S Legend is an advanced mobile suit built by ZAFT, based on the ZGMF-X13A Providence. The Legend is powered by a "hyper deuterion" reactor, which is a nuclear reactor that incorporates a derivative of deuterion beam technology for currently unknown purposes. It is uncertain whether Legend's hyper deuterion reactor includes a hyper capacitor like that of its companion unit ZGMF-X42S Destiny. The Legend is smaller and less bulky than its predecessor but it's speed and moblity have improved and is almost on par with the ZGMF-X20A Strike Freedom as seen when it battles it and also utilizes a refined version of its DRAGOON system which allows ordinary pilots to control multiple remote weapon pods. This technology was tested on the ZGMF-X3000Q Providence ZAKU. Legend has 10 DRAGOON pods, mounted on its backpack and waist. The beam spike weapons of Legend's two large DRAGOON pods are capable of penetrating the Positron Reflectors on EA mobile armors such as the YMAF-X6BD Zamza-Zah and YMAG-X7F Gells-Ghe. With a total of 26 beam machine guns, it is also armed with 2 head-mounted CIWS, 2 beam saber that can combine into a long two-bladed spear, and a long barreled high-energy beam rifle. For defensive purposes, it is equipped with 2 wrist-mounted beam shields.
The ZGMF-X666S Legend uses the operating system Gunnery United Nuclear-Deuterion Advanced Maneuver system.
Legend is piloted by Rey Za Burrel, stationed aboard the battleship Minerva. Initially, Athrun Zala was the designated pilot, but is later assigned to Rey after Athrun shows sign of defection. The Legend's combat debut is against a stolen ZGMF-2000 GOUF Ignited, piloted by Athrun Zala. It then participates in Operation Ragnarök, the invasion of Heaven's Base in Iceland, where it and Lunamaria Hawke's ZGMF-X56S Impulse assist Shinn Asuka's ZGMF-X42S Destiny in defeating the base's GFAS-X1 Destroy squad. Later, after being held in reserve for the initial stage of the battle, Legend is launched to participate in the invasion of Orb after the assault begins to go badly for ZAFT. After the firing of Requiem, the Minerva heads to space to participate in the battle near the Daedalus lunar base, and during that battle, the Legend defeated two GFAS-X1 Destroy units before destroying the retreating Girty Lue, killing Blue Cosmos/Logos leader Lord Djibril. The Legend is heavily damaged by Kira Yamato's ZGMF-X20A Strike Freedom, and is presumed to be destroyed in the destruction of the mobile fortress Messiah.
- Legend's head crest displays the text "X-666S SESSANTASEI", which means "sixty-six" in Italian and is a reference to Legend's model number.
- Legend's model number is the number of the devil (666).
- When Legend's existence was revealed to the public, but before its name was given out, many fans nicknamed it "Sin Providence", keeping with the trend of referencing Seed director Mitsuo Fukada's past series Cyber Formula.