Captain
The Captain is an expository character: his sole function is to establish Macbeth's martial reputation before the man himself appears. His graphic account of the battle shapes our first impression of the play's protagonist.
Appears In
Biography
The Captain is a wounded Scottish officer who appears briefly in Act I, Scene 2, delivering a vivid eyewitness account of the battle to King Duncan. He is sometimes called the 'Bleeding Captain' in stage directions.
His report introduces Macbeth to us before we meet the man himself — describing him as a prodigy of violence who carved his way to the rebel Macdonwald and 'unseamed him from the nave to the chops.' The image is graphic and deliberate: it establishes Macbeth's capacity for brutal, decisive action.
The Captain is then carried offstage for medical attention and does not appear again. His function is purely expository — he exists to tell us who Macbeth is before the witches complicate that picture.
Motivation
The Captain is motivated by loyalty to his king and by the simple desire to give an accurate report of what he witnessed. He is a soldier performing his duty even in the extremity of his wounds.
Personality
The Captain is a minor figure but not a thin one. His language is muscular and precise — the speech of a soldier who has seen things and knows how to describe them. His wounds give his testimony an authority beyond mere reportage.