The Strider is a large three-legged Combine Synth. The Striders serve as the Combine's main heavy ground assault unit. It is capable of pursuing hostiles in both confined streets and open plazas, even crouching down to fire at enemies who seek cover under overhangs or in bombed-out buildings. The Strider's body is covered in a smooth brown carapace or exoskeleton. On the "head" of the Strider is a rapid-firing pulse cannon, with a heavier warp cannon suspended below. The three long legs of the Strider are tipped with sharp spikes and a rosette of finer, hair-like spines.
While walking about or attacking, Striders produce many different vocalizations, such as growls, groans, whoops, and howls; when killed, they give a mournful cry. In addition, Striders will leak a yellow substance when damaged, and their carapace contains a large, somewhat human-looking brain.