Combat knives come in many shapes and sizes. Most militaries and governments today have standardized the types of combat knives issued to their infantry soldiers.
One famous knife, usually regarded as a combat knife is the Fairbairn-Sykes knife. Very much like a dagger in its thin, double-edged design, arguably, it is not a combat knife at all, since its purpose is silently killing an unprepared sentry or other foe, rather than fighting. Though it is quick and efficient for extremely close quarter combat nonetheless and it is commonly sold as such around the galaxy.