The Locust Horde is the antagonist faction of Gears of War: E-Day. This page covers the faction as this game presents it: a force emerging from underground on Emergence Day that nobody on the surface has a name for, a doctrine against, or any reason to expect. The per-unit roster is on Enemies.
Where They Come From
The Locust come from the Hollow, the space beneath the surface of Sera. On Emergence Day the ground breaks open across the entire planet, and emergence holes open anywhere the Locust choose to surface. In Kalona they arrive through tunnels beneath the streets, which is why the COG scanning devices at the centre of Horde Siege exist: they were built by mining companies to find Imulsion and are repurposed to map Locust tunnels under the city.
An Army, Not a Swarm
The central reveal of the campaign is what the Locust actually are. The invasion opens looking like a monster attack: waves of feral creatures, no weapons, no formation, no communication. Then Drones appear. Then the Drones pick up guns, take cover, use tactics that mirror how a squad of Gears would fight, and speak.
The studio describes deliberately building the arc so that the realisation lands late: it starts like a monster invasion, almost like a zombie film, and at some point it has to dawn on the characters that there is an army down there with commanders and structure, and that none of it is mindless.
Enslaved Creatures
The Locust do not fight alone. The game adds new creatures from the Hollow that the Locust have enslaved and unleashed on the surface. The team treats the Hollow as effectively unlimited creative licence, on the reasoning that anything could plausibly live underground and therefore anything could come out of a hole. Only one of these creatures has been named publicly: the Bile Frog, which spits acid.
The same logic shapes the Wretches. The design fiction for the first wave is that they were caged, starved into rabid attack dogs and released ahead of everything else, which is why they are drawn skinny and malnourished rather than as the armoured versions the series usually shows.
Naming the Enemy
Because this is first contact, none of the Locust units have names on the surface. The squad nicknames the creatures on the fly as they meet them, and those nicknames become the names. That is a narrative device and a design constraint at once: the game cannot use established terminology in dialogue until the characters have invented it.
Heavy Units and Bosses
Two large Locust are confirmed by name in a boss role, both through the Invasion Event system in Horde Siege: the Corpser and the Brumak. A Corpser also appears in the campaign as a set piece, ripping through the ground as a sky train collapses. Towering bosses are confirmed to exist in the campaign as well, but none of them has been named, and that gap is tracked on Campaign Bosses.
Locust Weapons
Some Locust equipment ends up in player hands. The Heavy Boomshot is the Locust Prototype Boomshot, carried by Boomers and classified as a Heavy Weapon. The Incinerator is a Locust shotgun that fires raw Imulsion. Both are listed on Weapons.
Scope Note
This page records the Locust only as this game presents them, at the moment of their first appearance on the surface. Later developments in the war belong to other entries in the series and are deliberately excluded, as is any material this game has not confirmed.