The Tokay Gecko, Gekko gecko, is a common house gecko that is native to Asia, has a widespread distribution across its native range, and also is invasive in Florida. The purpose of this research is to elucidate the ultrastructural changes that occur to spermatids during the process of spermiogenesis within the Tokay Gecko using transmission electron microscopy. Spermiogenesis is the final stage of spermatogenesis and is a reproductive process that mature spermatids undergo to become mature spermatozoa. This research is important because it will extend the knowledge of spermiogenesis within the Gekkonidae family, which previously had only one species account of spermiogenesis. This type of morphological data may also be valuable in future studies that incorporate the ultrastructural data gathered here for life history, phylogenetics, or histopathological research within reptiles. Testicular tissues from three G. gecko were collected from captive bred adult males at the University of Arkansas, fixed in Trumps fixative, and sent to Dr. Kevin Gribbins’ research lab at the University of Indianapolis. The tissues were processed for transmission electron microscopy. Images and the ultrastructural description of spermiogenesis in the Tokay Gecko were then compared to that of the Mediterranean Gecko, Hemidactylus trucicus, as well as other lizards in order to observe and compare similarities and difference between spermatid ultrastructure as they proceed through spermiogenesis.