Played by Diego Klattenhoff
Donald Ressler is a veteran FBI field agent who has been assigned to track Raymond Reddington for the bulk of his career. He was shocked when Reddington turned himself in - and frustrated when, despite his experience and expertise, Red refused to work with him directly. Initially antagonistic, even hostile, the relationship between Red and Ressler has become less strained over the last year - particularly after Red worked tirelessly to save Ressler's life during Anslo Garrick's siege of the Post Office, and later when Red helped bring the men who murdered his fiancée to justice.
Diego Klattenhoff stars as Agent Donald Ressler on NBC's "The Blacklist."
Klattenhoff recently appeared in the sci-fi film "Radius," directed by Caroline Labrèche and Steeve Léonard, which premiered at the 2017 Fantasia Film Festival. Recent film roles include the lead in the psychological thriller "Lavender," co-starring Abbie Cornish, Dermot Mulroney and Justin Long, and as the brother of Charlie Hunnam's character in Guillermo Del Toro's "Pacific Rim."
Klattenhoff played Mike Faber opposite Claire Danes, Damian Lewis and Mandy Patinkin in the critically acclaimed and award-winning Showtime series "Homeland," created by Howard Gordon and Alex Gansa ("24").
Also on television, Klattenhoff starred opposite Taylor Schilling on NBC's "Mercy" and has had memorable guest and recurring character appearances in series that include "Men in Trees," "Falling Skies," "Criminal Minds: Suspect Behavior," "24" and "ER."
Film credits include the 2010 Sundance Film Festival U.S. Dramatic Competition entry "The Dry Land," for which he received standout reviews, "The Informers," "Lucky Number Slevin" and "Unconditional."
Klattenhoff was cast to play series regular Brendan Casey in the 2009 HBO pilot "Anatomy of Hope," directed and produced by J.J. Abrams.