Gray the Ninelives is a member and the powerhouse of the Gung-Ho-Guns.

He possesses immense strength and his armor is considerably resilient, being made of a combination of metal and flesh. Despite his size, Gray also proved to be quite agile.

In the first anime, Gray is a humanoid cyborg with several weapons hidden inside his body. He also hides his brain on his hips, allowing him to control his legs even without his upper body. In the anime Gray doesn't speaks, but makes some creepy noises and even laughs at Wolfwood during their battle.

In the manga, Gray the Ninelives is a 7 foot 5 inch bulky muscular humanoid cyborg, wearing black leather or a vinyl makeshift jumpsuit with studs or bearings. His mouth devoid of lips, has a mostly vertical orientation with small thin teeths. His head and neck when stretched somewhat resemble a snake or worm. During his fight against Wolfwood, he wields two large gauntlets with built-in grenade-launchers.

In Trigun Stampede, it shows that Gray the Ninelives is now a enormous and heavy mecha, probably also being controlled by someone inside.

(Source: TRIGUN Wiki)