The Combat Knife is a specialized knife designed for combat purposes. Although a limited combat weapon, the Knife was nonetheless valuable when fighting Yautja, and could be used to cut through the net fired by a YautjaNet Gun.
In Aliens, Bishop uses a combat knife during a game of five finger fillet involving Private Hudson.
In Predator, the members of Dutch's team carry assorted combat knives, most notably Dutch himself, who uses his knife to pin a guerrilla to a pole during the assault on the rebel camp, and Billy, who attempts to face the Jungle Hunter armed only with his large combat knife.
In Aliens versus Predator 2, the Combat Knife is standard issue equipment for all Colonial Marines. It is mostly only suited to cutting away debris, but is also useful for silent kills against human opponents, against Chestbursters, and can be used to cut through the net fired by a YautjaNet Gun.