Gladius

Gladius is a member of the Donquixote Pirates' Pica's Army.

Appearance
Gladius wears a full body dark-colored coat, with metal rings on the arms and chest, and metal gears on the elbows, and matching boots. Gladius also sports a ninja mask, which is connected to a pair of goggles, covering half of his face, and a top hat, all giving him a very steampunk theme. He has spiky light colored hair that seems to be condensed inside the top hat. In the anime, his elbows seem to be completely mechanical.

Personality
Gladius, like most of Doflamingo's underlings, treats his leader with great respect, as he got angry when he noticed Violet's betrayal. He values punctuality as well as following and executing orders precisely, and despises those who do not live up to his standards.

Donquixote Doflamingo
Gladius has great respect for his captain, as he is quick to seek revenge for Violet's betrayal against him. Gladius also was overprotective enough to shoot Baby 5 when she was trying to kill Doflamingo, while the other members didn't seem to care.

Baby 5
Gladius and Baby 5 have a rather strange relationship. On the one hand, Gladius didn't seem to hesitate to go as far as shooting Baby 5 in order to protect his captain, and on the other, the two were seen a day later talking casually about Violet's betrayal.

Violet
Gladius seemed to trust Violet's abilities enough, in order to agree on her key role to defeat the Straw Hats. When the news about her betrayal arrived, Gladius seemed quite surprised, but was willing to act quickly and punish her for it.

Abilities And Powers
It seems that when Gladius gets angry, his hair grows to the extent of tearing his hat up. Whether this ability comes from a Devil Fruit, or even if it can be used effectively in a fight, is still unknown.

Weapons
Gladius has been seen using a pistol to shoot Baby 5.

Punk Hazard Arc
Gladius first appeared when Vergo called Doflamingo. As Baby 5 attacked Doflamingo, Gladius eventually shot her in order to get her to calm down.

Dressrosa Arc
Gladius was talking with Baby 5 about Violet's betrayal and what they should do about it. His top hat began to expand as he became more angry about it, until Baby 5 told him to calm down and not explode. His hair ultimately burst through it and he angrily expressed his disgust of people who don't follow orders.

Anime and Manga Differences
In the anime, Gladius' mask seems to cover his whole face. Also, the color of his mask and gloves is white in the anime, while in the manga they both are dark-colored to match his general attire.

Trivia

 * Gladius means sword in Latin, and usually refers to a Roman short sword roughly two feet long. It can also mean murder, death, or gladiatorial combat.