Kathleen Patricia McDonald O'Malley (born November 17, 1956) is a former United States circuit judge of the United States Court of Appeals for the Federal Circuit.

Born in Drexel Hill, Pennsylvania, O'Malley received a double Artium Baccalaureus degree from Kenyon College in Gambier, Ohio, in 1979, graduating magna cum laude and Phi Beta Kappa. She had majors in honors history and economics, and she graduated in both with distinction. She received a Juris Doctor from Case Western Reserve University School of Law, Order of the Coif, in 1982, where she served on Law Review and was a member of the National Mock Trial Team.^[2]

She was a law clerk to Nathaniel R. Jones of the United States Court of Appeals for the Sixth Circuit from 1982 to 1983. She was in private practice in Columbus, Ohio, from 1983 to 1991, first at Jones, Day, Reavis and Pogue, until 1985, and then with Porter, Wright, Morris & Arthur, where she became a partner, and had a practice with an emphasis on complex corporate and commercial litigations, including intellectual property, securities fraud, trade secrets, shareholder's rights and large-scale coverage disputes. She was chief counsel to the Ohio Attorney General's Office from 1991 to 1993, where she was responsible, under the direction of the Attorney General, for the overall functioning and management of all divisions of the Attorney General's Office, including litigation, law enforcement, legislative activities, policy initiatives and the human resources and administrative aspects of the office. From 1993 to 1994, she was Chief of Staff and First Assistant to the Attorney General, overseeing the work of the office's 350 attorneys and acting as Counsel of Record in the state's more sensitive and complex legal battles.^[2]