Helm, a medieval word for protective combat headgear. The medieval great helm covers the whole head and often is accompanied with camail protecting throat and neck as well. Two important helmet types to develop in antiquity were the Corinthian helmet and the Roman galea.

In the Middle Ages, many different military helmets and some ceremonial helmets were developed, almost all of these being made of metals. Some of the more important medieval developments included the great helm, the bascinet, the frog-mouth helm and the armet.

In its simplest form, the great helm was a flat-topped cylinder of steel that completely covered the head and had only very small openings for the eyes and mouth.

The great helm ultimately evolved from the nasal helmet, which had been produced in a flat-topped variant with a square profile by about 1180. The bascinet was a Medieval European open-faced military helmet. It evolved from a type of iron or steel skullcap.

Soon after 1450 the "great bascinet" was rapidly discarded for field use, being replaced by the armet and sallet, which were lighter helmets allowing greater freedom of movement for the wearer. However, a version of the great bascinet, usually with a cage-like visor, remained in use for foot combat in tournaments into the 16th century.