Sister Callista Roy is a prominent nursing theorist known for developing the Roy Adaptation Model. Born in 1939, she has made significant contributions to nursing education and practice, emphasizing the importance of adaptation in health care. Her model focuses on how individuals adapt to changes in their environment, promoting holistic care. Roy's work has influenced nursing curricula and research, highlighting the role of nurses in supporting patients' adaptation processes. She has received numerous awards for her contributions to the field, and her theories continue to be applied in various health care settings, enhancing patient care and outcomes.