The Twitcher is a variant of the Slasher Necromorph that appears in Dead Space and Dead Space 3. This particular variant is created from soldiers equipped with Stasis modules: devices that drastically stall molecular motion by producing a temporary time dilation. Stasis modules are meant to be used in an outward fashion such as slowing down attackers or criminals trying to escape, but the Necromorph contagion has fused the device to the user's body and somehow reversed its affects, causing the creature to accelerate to an alarming speed.
Twitchers are so named due to their spasmodic behaviour. When attacking, they constantly twitch and writhe as they run, yet somehow maintain their balance. Moving about so swiftly and sporadically, Twitchers can be difficult targets unless using a weapon with a wide range of fire. They have a higher rate of endurance compared to Slashers, thanks to both the Stasis module and the military body armour they wear.