The great white is classified as a mackerel (Lamnidae) shark. There are four other living species in this family, two mako and two Lamna sharks.

Dental features and the extreme size of both the great white and the prehistoric Megalodon led many scientists to believe they were closely related, and the name Carcharodon megalodon was applied to the latter. At present there is considerable doubt about this hypothesis, as many scientists would place the megalodon and white shark as distant relatives - sharing the family Lamnidae but no closer relationship. Latest research suggests that the great white shark is more closely related to the mako shark than to the megalodon. According to this theory, Isurus hastalis, is considered to be the true ancestor of the great white, while the megalodon has strong ties with the sharks belonging to Carcharocles genus. In this case, Otodus obliquus is considered to be the ancient representative of the extinct Carcharocles lineage.

Information taken form Wikipedia