Final answer:
Banquo is the Scottish thane and Macbeth's co-general who is murdered by Macbeth because the witches' prophecy suggested Banquo's children would be kings.
Step-by-step explanation:
The Scottish thane and Macbeth's co-general in wars, who is murdered by Macbeth due to the prophecy that his children would be kings, thus posing a threat to Macbeth's rule, is Banquo. Banquo is initially presented as Macbeth's friend and a noble general; however, after the witches predict that Macbeth will be king, they also suggest that Banquo's descendants will inherit the throne. Macbeth sees Banquo's potential offspring as a threat to his newly attained power, leading to Banquo's murder - a pivotal moment in the play 'Macbeth' by William Shakespeare.