Ka-Bar is the contemporary popular name for the combat knife first adopted by the United States Marine Corps in November 1942 as the 1219C2 combat knife, and subsequently adopted by the United States Navy as the U.S. Navy utility knife, Mark 2. Ka-Bar is the name of a related knife manufacturing company, Ka-Bar Knives., Inc., of Olean, New York, a subsidiary of the Cutco Corporation.

A knife is a tool or weapon with a cutting edge or blade, usually attached to a handle or hilt. One of the earliest tools used by humanity, knives appeared at least 2.5 million years ago, as evidenced by the Oldowan tools. Originally made of wood, bone, and stone, over the centuries, in step with improvements in both metallurgy and manufacturing, knife blades have been made from copper, bronze, iron, steel, ceramic, and titanium. Most modern knives have either fixed or folding blades; blade patterns and styles vary by maker and country of origin.