Horsa, according to tradition, was a fifth century warrior and brother of Hengest who took part in the invasion and conquest of Britain from its native Romano-British and Celtic inhabitants. He is said to have died in battle in Kent, and a monument was raised in his memory.

Twins of warriors is a common theme in folklore, and because our earliest witness to Horsa's existence, Bede, mentions a stone existed that recorded his name, recent scholars have speculated that his name came from an Roman inscription which was illegible except for part of the latin word for cavalry -- cohort.