Hardy, an only child, was born in Hammersmith, and brought up in East Sheen, London. His mother, Elizabeth Anne (née Barrett), is an artist and painter whose family was Irish Catholic. His father, Edward "Chips" Hardy, is an advertisement and comedy writer. Hardy studied at two private schools, Reed's School and Tower House School, then at Richmond Drama School, and subsequently at the Drama Centre London. He began his career in war dramas, winning the part of United States Army Private John Janovec in the award-winning HBO and BBC miniseries Band of Brothers. He made his feature film debut in Ridley Scott's 2001 war thriller Black Hawk Down.
In 2002, Hardy appeared in the independent film Dot the i, sharing the bill with Gael García Bernal. He then travelled to North Africa for Simon: An English Legionnaire, a story of the French Foreign Legion. In the same year, he gained some heavy international exposure as the Reman Praetor Shinzon, a clone of USS Enterprise Captain Jean-Luc Picard (Patrick Stewart) in Star Trek Nemesis. He returned to England to feature in the 2003 thriller LD 50 Lethal Dose.
In 2002, Hardy appeared in the independent film Dot the i, sharing the bill with Gael García Bernal. He then travelled to North Africa for Simon: An English Legionnaire, a story of the French Foreign Legion. In the same year, he gained some heavy international exposure as the Reman Praetor Shinzon, a clone of USS Enterprise Captain Jean-Luc Picard (Patrick Stewart) in Star Trek Nemesis. He returned to England to feature in the 2003 thriller LD 50 Lethal Dose.