Iain De Caestecker is a Scottish actor. He is best known for portraying Leopold Fitz/The Doctor in the television series Agents of S.H.I.E.L.D. (2013–2020). He is also known for his roles in Coronation Street (2001–2003) as Adam Barlow and the films Shell (2012), In Fear (2013), Not Another Happy Ending (2013), Lost River (2014), and Overlord (2018).

Leopold James "Leo" Fitz is a fictional character that originated in the Marvel Cinematic Universe before appearing in Marvel Comics. The character, created by Joss Whedon, Jed Whedon and Maurissa Tancharoen, first appeared in the pilot episode of Agents of S.H.I.E.L.D. in September 2013, and has continually been portrayed by Iain De Caestecker.