Antetokounmpo was born in Athens, Greece to Nigerian parents. His father, Charles, is a former Nigerian soccer player, while his mother, Veronica, was a high-jumper. He officially gained Greek citizenship on May 9, 2013, with the official legal spelling of his last name being Antetokounmpo.
His younger brother, Giannis (b. 1994), was drafted 15th overall in the 2013 NBA draft by the Milwaukee Bucks. With Giannis known as "The Greek Freak", Thanasis is sometimes referred to as "Greek Freak 2", although his own nickname is "The Greek Streak". In addition, he's also the older brother of Kostas and Alexis, both of whom also trained with Filathlitikos. Antetokounmpo's mother gave each of her four sons born in Greece, both a Greek and a Nigerian name. In 2017 during the Eurobasket tournament in Helsinki, where the Greek National Basketball team was playing, he was nicknamed by the basketball sportcaster Vangelis Ioannou as well as by his brother Giannis as "The Elevator" due to his superb athletisism and jumping skills
