After the debacle which destroyed a major part of the G.I. J.O.E. force, General Joe Colton called upon some retired Joes. One of these old geezers was William Garrett, Codename GRIZZLY.
Therefore, Grizzly is an original character, an off-screen character in the Retaliation storyline.
Grizzly is based on a 30th Stalker body with added accessories such as a combat vest, scarf, rappelling harness with custom-made belt loop for a machete. The strap of the goggles on his ProTec helmet has been replaced with elastics and fits snugly around the helmet.