General Mantis is a Crenga - a genderless species - and a "villain" in the Skulduggery Pleasant series. Mantis is tall, pale, with long arms and legs, and wears a gas mask. Mantis is the primary antagonist for the first part of Last Stand of Dead Men.
Mantis is not technically a villain, as it does not commit "evil" actions from it's, or it's people's point of view, and is merely on the opposing side of the main characters.
The War with Mevolent
During the war with Mevolent, General Mantis was one of the top tacticians for the allies. Due to it's incredible tactical genius, the allies never lost a battle while Mantis was in command.
Last Stand of Dead Men
After the war between the sanctuary begins, General Mantis is told by The Supreme Council that he will be leading the charge in attacking Ireland, Mantis goes with his army using the Midnight Hotel's teleportion to get through the shield, Mantis fights Billy-Ray Sanguine when he takes out the shield and easily defeats him, Mantis army fights against the Irish army multiple times, even taking Valkyrie, Tanith, and one of the Monsters Hunters hostage at one point.
Eventually, after surrouding Roarhaven, the war ends and Mantis joins up with Erskine Ravel to celebrate the newfound peace. During the battle with the Warlocks, Mantis decides that he and his elite team will go and take out Charivari, though they are defeated by the Warlocks and burnt at the stake, Skulduggery shoots Mantis and his allies in order to stop them from having to die a horrible torturous death.