Unlike his parents, both of whom are doctors, Iain De Caestecker fell for acting since he was a kid. He began his acting career early on, landing a small part in the 2000 film "The Little Vampire". This was followed by minor roles on the United Kingdom television shows "Coronation Street" and "Lip Service". In 2011, he secured the lead roles on BBC sci-fi series "The Fades" and the three-part BBC series "Young James Herriot". The latest feature earned him a nomination for a British Academy Scotland Award.

Caestecker continued starring on the miniseries "The Secret of Crickley Hall" and in feature film "Shell" afterwards. Then, he was billed to portray the character of Agent Leopold Fitz on ABC adventure television series "Agents of S.H.I.E.L.D." The show became a smash and thus helped catapulting Caestecker to stardom. He next was cast to star in Ryan Gosling's directorial debut "Lost River" (2014).

Caestecker was born on December 29, 1987 in Glasgow, Scotland. He has a twin sister named Nicky.