Final answer:
In 'Macbeth', Malcolm's first lie is his account of the Thane of Cawdor's noble and repentant death, which is revealed to be fabricated.
Step-by-step explanation:
Malcolm's first lie in the play 'Macbeth' by William Shakespeare is his fabricated tale of the noble death of the Thane of Cawdor. In lines 130-131, Malcolm lies about the Thane of Cawdor's final moments. According to Malcolm, the Thane faced his death with such dignity that 'nothing in his life / Became him like the leaving it.' Malcolm claims the Thane confessed his treason, implored the king's pardon, and exhibited deep repentance. However, in the guide provided, this account is identified as untrue.