Myra Clark Gaines (c. June 30, 1804 – January 9, 1885) was an American socialite and plaintiff in the longest-running lawsuit in the history of the United States court system. From 1834 to 1891, Gaines was at the center of a legal battle to recognize her legal status as the sole heir of her deceased father's estate and recover valuable land in New Orleans. During its 57-year history in the courtroom, the Gaines cases appeared before the Supreme Court seventeen times and the Louisiana state and federal court at least seventy times. The Gaines cases are notable not only because of their length and complexity but also due to the controversial image and perseverance of Myra Clark Gaines herself, particularly at a time when women were confined to a domestic, dutiful ideal of femininity.