I made this out of necessity for a fanfic I'm writing. Beyond his cannon information, I named him (Miles) and gave him a face: According to how I described him, he has rough, olive-toned skin, with cobalt eyes and black hair dressed in a squared-away style (think like how Carter has his hair cut). He has a scar that runs across his nose and left cheek, a cut on his lower lip, and a burn mark that goes down his neck to where the neck connects to the shoulder.
His armor is the one I usually use in the game: Mk V (b) base with steel as a primary color and white as a secondary. The helmet is the Up-Armored variant, and he has a few utilities like ammo holders, a knife holster, some pouches, and a display on his wrist (like Carter's).
For weapons, he usually arms himself with two primaries, a secondary, and a melee. His main primary is a DMR, then an Assault Rifle. His sidearm is usually an M6G Handgun (the Reach magnum), and he occasionally carries other weapons scavenged from enemies, where necessary. His knife is a standard UNSC combat knife, upscaled for Spartan proportions. The sheath is constructed in such a way that the edge is sharpened as it's drawn, ensuring it's always ready for use.
I'm still hammering out a sordid backstory, so let me know if you wanna see what I have so far.