The longest male and female alligators (Alligator mississippiensis) measured in Florida during 1977-1993 were 426.9 cm and 309.9 cm total length. The heaviest male and female alligators weighed 473.1 and 129.3 kg. A predictive model for calculating total length from head length is presented. Estimated total lengths for three large alligators described in the literature were substantially shorter than reported lengths. The longest alligator for which a total length can be corroborated from skull measurements was 454 cm. We discuss the plausibility of past reports of exceptionally large alligators with respect to verified lengths of specimens, harvest pressure, growth patterns, and longevity.