A kingdom for a stage, princes to act

And monarchs to behold the swelling scene!

Then should the warlike Harry, like himself,

Assume the port of Mars; and at his heels,

Leash'd in like hounds, should famine, sword and fire

Crouch for employment.

This excerpt mostly introduces

Answer: This excerpt mostly introduces the character of King Henry, or Harry.

Explanation:

This is an excerpt from the prologue of Henry V, Shakespeare's history play. The play tells the story of King Henry V of England, and is set during the Hundred Years' War, before and after the battle of Agincourt (1415).

In this excerpt, King Henry is referred to as Harry. The speaker, a character named Chorus, describes King Henry as warlike and powerful, which introduces us to his character. Henry is the protagonist of the play and Chorus thus celebrates his greatness and tells us about his virtues.