I'll start off with my own character.
Position: Commander for Grim Reaper's Angels
Appearance and background: Zeros cuts a regal sort of figure, almost like the vampires described in some ancient texts and scrolls. Unlike many of his other brothers, Zeros kept his jet black hair a little longer than most, allowing for a breeze to spread it from his angular features. Like his other brothers, his incisors were fairly longer than other space marines, only adding to that vampiric appearance. Zeros' midnight black eyes cut into the very depths of his enemies, imposing a dreading fear that rarely could be shook. These same eyes saw to it that his own men followed orders without question and ordinary men obeyed just to keep from staring at him. For all his years at war, Zeros' face was largely unmarked by any scars. Zeros' history is long and wide, dating back to the time of the Horus Hersey. He raised through the ranks like any other marine would in service to the mighty Blood Angels, passing all trials put before him through sheer determination and will. When the death of Sanguinius had come to pass, Zeros and many of his fellow marines succeeded from the Blood Angels, forming their own chapter the Grim Reaper's Angels, taking after a figure from ancient Terra scrolls. Zeros took command of his newly founded chapter and as such, they traveled the galaxy, ridding the Imperium of Man of her many enemies. After a run in with the forces of chaos, Zeros became separated from the rest of his forces, his men thinking him lost to the warp. He returned much later, the flow of time in the warp such a fickle thing that while it was a short time to Zeros, much more time had lapsed within the realm of realspace. Establishing communications and connections with some of the other chapters of space marines, Zeros was able to link back up with his own beloved chapter, taking the reigns once more. Though he had survived in the warp, his men had noticed something changed about him. Not only his armour but with his personality as well. He seemed somehow colder, even towards his own men. While he still fought for the Imperium, slaying all those that stood before him, he did it with too much of a cold rage. Innocents and bystanders on populated worlds had once been regarded in the planning and tactics, the deaths of which were avoided at all costs. But now, now the civilians' blood ran in equal measure with that of the enemy.
Wargear: Zeros favors a modified version of Mark VII power armor. The power supply is greatly modified and looks almost alien, the identity of the actual power itself was not known. What was known was that it powered his armour just fine but in addition lent a protective barrier molecules thick that would gleam like a oil on water if struck but then fade to nothing and ordinary eyes could pick up. In addition, this same power could be put to the offensive, shrouding Zeros' lightning claw, Reaper's Claw, in a field equal to that of a normal power weapon. The power also fed into a peculiar pistol that Zeros had named Soul Shredder. The weapon contained the same power as an inferno pistol but a range shy of that for a regular bolter.
"There is a cancer eating at the Imperium. With each decade it advances deeper, leaving drained, dead worlds in its wake. This horror, this abomination, has though and purpose which functions on an unimaginable, galactic scale and all we can do is try to stop the swarms of bio-engineered monsters it unleashes upon us by instinct. We have given the horror a name to salve our fears; we call it the Tyranid race, but if it is aware of us at all, it must know us only as Prey."