Nicholas Dimitri Constantine Galitzine was born on 29 September 1994 in Hammersmith, London, England. His father, Geoffrey Leo Alexander Galitzine, is a co-founder of a glass-recycling company and a former financier in the city of London. Nicholas’s grandfather changed his name from Edward Ralph Alexander Tier to Edward Ralph Alexander Galitzine on 9 April 1956. Nicholas’s traceable paternal ancestors are British. His mother, Lora Maria Konstantina Papayanni, is an American of Greek descent. Growing up, Galitzine visited his relatives in the Peloponnese, Athens, and the islands during the holidays, which helped him get in touch with his Greek heritage. He has an elder sister named Lexi Galitzine, who is an illustrator and interior stylist. Galitzine attended Dulwich College. In his childhood, he played rugby and football, and participated in county-level athletics competitions. He played for the Harlequins Academy until an injury to his rotator cuff made him stop playing sports.