Final answer:
In the play Macbeth, Lady Macbeth expresses agonizing remorse for contemplating killing an innocent child.
Step-by-step explanation:
In the play Macbeth, the character who expresses agonizing remorse for contemplating killing an innocent child is Lady Macbeth. In Act 2, Lady Macbeth questions Macbeth about the crying of the children and the murder of Duncan. She reveals her own feelings of guilt and remorse for planning the murder and mentions that she could not go through with killing the innocent child because it reminded her of her father. This scene highlights Lady Macbeth's inner turmoil and remorse for her actions.