Final answer:
The character introduced as a brave and loyal servant to the King in "Macbeth" is Macbeth himself. He is initially depicted as a valorous and trustworthy nobleman, praised by other characters such as King Duncan and a sergeant.
Step-by-step explanation:
The character in "Macbeth" who is introduced as a brave and loyal servant to the King is Macbeth himself. Initially, Macbeth is portrayed as a valorous and trustworthy thane.
This is evident when Duncan refers to Macbeth with high regard, calling him ‘My worthy Cawdor,’ acknowledging his service and loyalty. Furthermore, before the unfolding of Macbeth's tragic ambition, he is described as a courageous fighter on the battlefield, which is echoed through various characters’ praise.
The impression of Macbeth's bravery is supported when a sergeant reports his valorous actions in battle to King Duncan, praising him as a ‘good and hardy soldier.' Despite his subsequent downfall, Macbeth's introduction in the play is unequivocally that of a respected nobleman admired for his devotion to the king and prowess in combat.