Dr. Thomas Herbert Crook III, aged 65 years, died unexpectedly on 22 September 2010. He was not only a loving husband, father and grandfather, but also a true gentleman who was kind and generous and genuinely concerned for the welfare of others. He will be profoundly missed by many. In his personal life, Dr Crook was an avid reader, hunter, and football fan. He enjoyed interacting with others and could readily strike-up a conversation with total strangers. He had an extraordinary depth of knowledge about a wide range of topics from history to politics to neuroscience, and enjoyed exchanging ideas with others. He always had a personal experience to share on many of these topics that was always enjoyable to hear.Professionally, Dr. Crook received his Ph.D. in Psychology from the University of Maryland in 1977. He was a clinical psychologist with more than thirty years experience in research related to the diagnosis, assessment, and treatment of adult-onset cognitive disorders. Dr. Crook served fourteen years at the National Institute of Mental Health (NIMH) where he held the position of Chief of the Institute's Geriatric Psychopharmacology division. He subsequently established the Memory Assessment Clinics, Inc., with offices across the U.S. and in Europe. Dr. Crook was the developer of the Psychologix test battery which is used for evaluation of age-related memory changes. For the last 4 years, he served as the Chief Executive Officer of Cognitive Research Corporation, St Petersburg, FL, where he worked with pharmaceutical, nutraceutical, and small biotechnology companies in the development and evaluation of treatments for cognitive disorders. Dr. Crook authored or co-authored more than 200 scientific papers and eight books. He delivered more than three hundred invited academic lectures around the world and recently presented lectures in India and Indonesia. Over the years, he appeared as a guest on numerous television shows including Good Morning America, The Today Show, CBS This Morning, and ABC 20/20. Dr. Crook's work on topics such as memory and aging also appeared in many non-scientific publications, including Newsweek, Time, U.S. News and World Report, Forbes, Fortune, Esquire, and Vogue. The last few years, he served as the "Head Coach," writing a monthly column for the general population in the magazine Prevention. Dr. Crook has served as a valued consultant to most of the world's major pharmaceutical companies and to governmental agencies including the National Aeronautics and Space Administration (NASA) and the U.S. Food and Drug Administration (FDA). He served as the Chairman of Task Forces formed by both the NIMH and the American Psychological Association to address issues related to cognition and aging, and he played a major role in establishing the guidelines used in the diagnosis and treatment of adult-onset cognitive disorders such as Age Associated Memory Impairment. Dr Crook is survived by his loving wife, Kay Grant Crook, and by his 5 children and the 7 grandchildren that he adored.