Gray

Gray is a spartus that could be summoned by Roman demigod Frank Zhang in The Son of Neptune. He is similar to the ones that appear in The Titan's Curse.

The Son of Neptune
After Frank manages to be the first person over the wall of the enemy fort and win a war game (similar to Capture the Flag) at Camp Jupiter, Mars appears on the battle field and claims Frank. Mars gives him his M-16 which turns into a dragon tooth tipped spear when he learns that Frank hasn't learned the family gift. He tells Frank that the spear has only three charges, meant to give Frank time to discover his family gift.

When fighting a group of Basilisks outside Iris' R.O.F.L shop, Frank stabs the spear into the ground and a Skeleton Warrior appears. Frank orders him to kill the basilisks. The skeleton warrior does as ordered and while sinking back in the ground, Frank asks his name and he smiles when Frank asks if it is Gray.

Frank uses the spear again when he wants to distract a small group of Laistrygonian Giants, but Gray ends up killing them instead. The last charge is used when a group of Gryphons knock over a train in Alaska and Frank calls on Gray to defend the mortals.

Abilities
Being dead, Gray is immune to poison and many other things and may not feel any pain at all, as shown when the Basilisk venom didn't effect him even as it melted his flesh or when he pulls out his own ribs to use as weapons. He is an incredibly fast and efficient warrior, dispatching powerful foes in seconds.

Trivia

 * Gray seems to be the only being able to kill monsters longer than a few moments as the Laistrygonian Giants and the Basilisks didn't immediately reform like other monsters in The Son of Neptune. This may be because he scattered the dust they dissolved into.