Sergeant Melanie Williams is Molly and Emily's older sister who is a strict millitary drill sergeant. She is the aunt of Jack, Melissa, Nightmare and Kino Darcy and the step aunt of Lorcan Darcy, whom she extremly hated. She appears in The Medieval Journey as one of the two main antagonists. She became shocked that a vengeful Lorcan appeared and betrayed her so she can rescue the Power Rangers as a thanks.
She returns in Lorcan Darcy's Adventures 2: One Last Game as the secondary antagonist. She is one of the villains who're shocked that Lorcan is a girl. She made her final appearance in Everything's Begun, the finale of Lorcan's story as the main antagonist. With her bossy attitude, She becames the main antagonist of The Purple Darcy: The Story of Lorcan Darcy.