By definition, supercentenarians are those persons who have reached the living age of 110 years or beyond. These are quite rare individuals indeed. Compare this to the average life expectancy worldwide of 71.4 years and in the United States of 78.9 years. And compare to the prevalence estimate of living centenarians, those individuals who reach 100 years and beyond, worldwide, which is between 350,000 and 450,000. It has been estimated that only about one in 1,000 of these centenarians lives long enough to become supercentenarians. This entry presents prevalence estimates, a description of these unique individuals, ideas as to the reasons for their extreme successfulness in aging, and attempts to convey what we can learn from such remarkable persons.