Nancy O'Reilly was the sister of Blackie O'Reilly and the lover of Jean Renault.


Nancy clung to Jean's side and threatened Emory Battis when Jean requested he bring him Special Agent Dale Cooper.[1]

With Jean, she plotted to kill her sister.[2]

She later encountered Dale Cooper, who restrained her and commanded her to take him to Audrey Horne. She did so and drew a knife when he went to the bed. She prepared to stab him, but he subdued her.[2]