Final answer:
In Shakespeare's play (A) 'Macbeth,' the Thane of Cawdor is the character who betrayed the Scots to the Norwegians and was executed for treason. His title is then granted to Macbeth.
Step-by-step explanation:
The character who betrayed the Scots to the Norwegians and was subsequently beheaded as a traitor in Shakespeare's play is the Thane of Cawdor. In "Macbeth," Duncan expresses his disappointment in the former Thane for deceiving them, and then he bestows the title of Thane of Cawdor upon Macbeth as a reward for his bravery in battle.
Throughout the play, the Thane of Cawdor is repeatedly mentioned as a traitor whose title is given to Macbeth, leading to a series of events driven by ambition and prophecy.