The Hunter, originally known as the Mini Strider, is a fast and efficient synth used by the Combine as a scout and escort. The Hunter is first seen in Mossman's message in Episode One, but not encountered directly until Episode Two, wherein it is a prominent enemy, making several appearances. The Hunter's body is somewhat rounded in shape with a shiny, metallic blue-green exoskeleton encasing it and three muscular legs attached to the sides and back of the body. On either side of the Hunter's body are what appear to be three pairs of compound eyes and a pair of vertically aligned fléchette launchers on the Synth's front. Located directly underneath the launchers are two small limbs tipped with metal blades for impaling targets, behind those and on the back are two oval shaped orifices possibly for breathing, vocalizations, or both. It is seen when a Hunter impales Alyx Vancewith these limbs. Similar to Antlion Guards, Hunters are heavily armored, and take reduced damage from most forms of small arms fire.Like all Synths, Hunters possess a number of vocalizations, all of which are shrill, fierce, and slightly electronic. They also appear to secrete some sort of white fluid, maybe blood, when shot.
Source: Combine OverWiki