Casting
John Eisendrath told Collider that the casting process was difficult. In February 2013, he and Bokenkamp invited Kiefer Sutherland, Bryan Cranston, Pierce Brosnan and Richard Gere to apply for the role of Raymond Reddington. In an interview to Variety, Bokenkamp told about his intentions to cast Sutherland for the role, though he also expressed doubt about the significance of the role to all these actors. At last, three days before filming began, they contacted James Spader to see if he would be interested in playing Reddington. After a lengthy remote conversation, Bokenkamp and Eisendrath cast Spader, as they felt confident in his understanding of the character. Spader's vision was for the international criminal to be a bald or short-haired person wearing a hat. The producers rejected his idea, however, Spader insisted on trying on a fedora while screening the pilot; later, the crew felt the hat enhanced Reddington's image and agreed to keep it. In an interview on Late Night with Seth Meyers, Spader admitted that he had gotten into the role of Reddington over the nine seasons; he also noted that to play his role plausibly at the beginning of season nine, he spent a considerable amount of time alone and not appearing on set. Co-star Harry Lennix said about Spader, "Oh my God. It's like playing basketball with LeBron James. Or baseball with Joe DiMaggio. He's tremendous. He's a master. He elevates everybody that's around him."
Although showrunners attempted to search for a more established actor as they cast Reddington, they invited more obscure performers for the role of FBI profiler Elizabeth Keen. Megan Boone got to know about the role by chance, and she instantly became passionate about it. She had taken a week to prepare for her audition as Keen and had been called back multiple times before she received the role in March 2013. Eisendrath recalled that he and Bokenkamp found "something specific" about Boone, and they got comfortable with her playing of the character. In 2015, Boone revealed her pregnancy which was implemented as a season 3 plot point. She was absent in a part of the season with her character killed, while her subsequent return was kept in secret from the cast. In June 2021, it was revealed that Boone would be leaving the series after season 8, which was initially written to be focused on her departure so as to close the storyline of Elizabeth.
On March 11, 2013, Ryan Eggold accepted the role of Tom Keen, Elizabeth's husband, who has previously worked for Reddington as a spy. In the middle of season 4, Eggold left the series to star in The Blacklist: Redemption, a new spin-off centered on his character, but returned later this season following the cancellation of Redemption. He was ultimately written off the next season. In a 2021 interview, he spoke about an option to return to the series, perhaps as a guest star, stating that it was "not totally out of the realm of possibility".
On March 13, 2013, Diego Klattenhoff joined the series as Donald Ressler, a law-abiding field agent working with Cooper's task force.
The next day, on March 14, 2013, Harry Lennix was cast as Harold Cooper, the leader of a newly formed task force, which cooperates with Reddington. Lennix has appeared in each season of the series; in an interview with Collider, he stated that he would be willing to continue his role into the show's twentieth season, like his favorite TV show, Gunsmoke.
On July 25, 2013, Parminder Nagra joined the cast as Meera Malik, a professional field agent who decides to help Elizabeth settle into her new job. However, she was written out of the series after the first season. Eight years after her departure, Anya Banerjee joined the series for the tenth season in a role of Meera's daughter, MI-6 intelligence officer Siya Malik.
On October 8, 2014, Amir Arison was promoted to a recurring role as Aram Mojtabai, a quirky technician and a professional computer master after he showed some extraordinary on-the-move improvisation skills in his debut episode. He was promoted to series regular on May 20, 2014. After the finale of season 9, Arison departed the series, but return appearances were left possible.
Hisham Tawfiq's appearance as Dembe Zuma was never presumed to exceed a one-time guest appearance. However he managed to prolong his contract first as recurring for the first two seasons, and, on March 31, 2015, earned a place in the main cast. He also noted that producers and scriptwriters gave him permission to alter the story and the past of Dembe based on his own insight and life experience.
Mozhan Navabi joined the cast for the second season on July 29, 2014. Various news sources confirmed that the name of the character she would reprise was Tamar Kartzman, until it was initially changed to Samar Navabi. Samar was a field professional agent recruited by the task force Director and originally working for Mossad who develops relationships with Aram. She officially confirmed her departure on March 29, 2019, in the middle of the sixth season. She returned once, in 2022, during the show's ninth season.
On May 7, 2020, Laura Sohn was promoted to series regular as Alina Park, another new field agent taken into Cooper's task force, also previously recurring in the seventh season. She departed after the series' ninth season.
The first season introduced several well-known actors in recurring roles. For the pilot, Ilfenesh Hadera was cast alongside Harry Lennix, playing Jennifer Palmer, a federal agent and a friend of Elizabeth. Alan Alda was cast in a major supporting role in September, as Alan Fitch, the Deputy Director of National Intelligence and one of Red's former allies. To bring the series closer to reality a former CIA agent, Bazzel Baz, was hired by the producers to teach CIA techniques on assaulting buildings to the crew. Baz instead contacted old associates for the scenes, and went on to play a role in the show that was similar to his own experiences in the CIA. Chin Han and Margarita Levieva were among the blacklisters besides Peter Stormare as Berlin. Susan Blommaert and Teddy Coluca also began starring as Reddington's valuable team members.
For the second season, Mary-Louise Parker was cast as Carla Reddington, one of Red's ex-wives. The episode "Luther Braxton" introduced David Strathairn in a guest role of Peter Kotsiopulos, the Director of the National Clandestine Service. Reed Birney played the final blacklister of season two, Tom Connoly, and his death scene in the season finale was met with a standing ovation from the crew. Stormare continued to recur through the season and later departed in the middle of it.
The third season featured numerous celebrities in major recurring roles as well as provided various comebacks of familiar characters. Deirdre Lovejoy was cast as White House Counsel Cynthia Panabaker, set to replace Adriane Lenox, who had left earlier this season. Fisher Stevens debuted as Marvin Gerard, an imprisoned criminal attorney joining Reddington's criminal empire, in the eponymous episode of the third season. Two actors portraying former blacklisters, Lance Henriksen and Margarita Levieva, returned during the third season. Strathairn also returned as one of the lead villains of the season, with two back-to-back episodes under his Blacklist number. The season also featured most of the lead cast from the series' spin-off, The Blacklist: Redemption. In July 2015, Edi Gathegi was revealed as a high-class operative and assassin set up to kill Elizabeth. Famke Janssen was cast as Susan Hargrave, an authoritative criminal magnate and Tom's mother. Ulrich Thomsen served as the blacklister in the finale.
The fourth season opened with the misleading departure of Blommaert after her character Mr. Kaplan was seemingly shot by Reddington. However, Kaplan remained alive till the end of the season. In August 2016, Leon Rippy joined as a ranger and her savior, Hunter, while Enrique Murciano landed a role as Julian Gale, an FBI investigator who previously worked with Ressler on capturing Reddington, in February 2017. Thomsen continued his role as Alexander Kirk, Liz's presumed father, who had been holding her hostage. He left the series in the first half of the season, although the fate of his character remained undisclosed. In the finale, Bazzel Baz, Murciano and Blommaert departed from the series.
The fifth season brought more new recurring characters. In August 2017, it was announced that Michael Aronov, and Aida Turturro would take the recurring roles of Smokey Putnum, the logistician and an embezzler, and Heddie Hawkins, his accountant. In October, Jonny Coyne was cast as Red's nemesis and Tom's murderer, Ian Garvey; his adopted daughter, Lilian Roth, actually Liz's halfsister, Jennifer Reddington, was portrayed by Fiona Dourif. Jonathan Holtzman and Genson Blimline also began starring in recurring capacities as two Reddington's operatives. Nathan Lane played a notable blacklister for the series' 100th episode. John Waters and Julian Sands appeared in season conclusion with Sands portraying Sutton Ross, a spy trying to take revenge on Reddington and the eventual blacklister of the finale. Janssen also returned for one episode.
In the sixth season, Dourif continued to recur in the season while Aronov departed. In November 2018, it was revealed that Coy Stewart would play Vontae Jones, Reddington's innocent cellmate Reddington meets and befriends while in prison. Stacy Keach played financier and con man Robert Vesco, who in real life escaped without payment of $200 million from the U.S. and who was rumored to die from lung cancer in 2007, amidst theories about his pseudocide. In two back-to-back episodes, the series connects Vesco and Reddington as Red searches for a lost treasure. Bokenkamp said about the two actors: "Spader and Keach together are a delight!". Laila Robins also appeared in the season's final minutes as Liz's mother, Katarina Rostova, a subject of the show's major story line.
For the seventh season, Robins was given a recurring role. The Blacklist's showrunners told Deadline and Variety that they were trying to change the format of the series to a family drama, rather than a crime drama as it was intended to be. It was the reason for the introduction of Rostova, who also served as the lead villain of the season. Brett Cullen starred in the season as Ilya Koslov, a person previously pretending to be the real Reddington. In December 2019, Joely Richardson was cast as Cassandra Biancchi, an international thief and the ex-girlfriend of Reddington, for a special episode partly based on Agatha Christie novels. Today host and meteorologist Al Roker appeared in the series' 150th episode as himself.
In the eighth season, various familiar actors returned in guest roles because it was the last season of the original storyline. The series continued casting new characters as well. Reg Rogers was cast in the role of the main antagonist, the mentally disordered crime lord Neville Townsend, who sought revenge on Red after he murdered his family and who launched a bounty hunt on Katarina Rostova. One of his bodyguards, who also assisted in the murder of Elizabeth, Elias Vandyke, was played by Lukas Hassel. Blommaert returned in a guest appearance in the season, as a hallucination of Mr. Kaplan coming for Liz. Dourif also made a cameo appearance in the season. The penultimate episode brought back Robins (who departed after the second episode of the season), Thomsen, and Cullen. Robins was revealed to be Tatiana Petrova, Katarina Rostova's body double, instead of Rostova herself.
In the ninth season, while casting continued for new roles, most of the recurring characters of the previous seasons, such as Lovejoy, Turturro, Holtzman, Blimline and Coluca, maintained their roles. Blimline, whose character died offscreen, departed at the end of the season. In October 2022, Diany Rodriguez and Karina Arroyave revealed that they would be starring in the upcoming season as Cuban sisters Weecha and Mierce Xiu, respectively. Keach and Richardson both returned for one episode. Stevens also left the series after the ninth season's finale which had the title addressed to his character. However, he was still nominated for the 47th Saturn Awards for best guest starring role. Han also returned in the finale, when his character, after being incarcerated for 10 years, escapes from prison and starts gathering blacklisters from all over the world to avenge Reddington.
Two major recurring stars died while starring. Clark Middleton, who played Glen Carter, Reddington's tracker and one of his best friends, from the second to the seventh seasons, and he was scheduled to appear in season eight, but died of West Nile virus in 2020, before the season was filmed. He was honored by the series in one of the episodes of season eight, as his character also died of the same virus; Huey Lewis also appeared as himself. Brian Dennehy, who played Elizabeth's grandfather and Rostova's father, Dominic Wilkinson, also died in 2020. He appeared in guest roles from the third to the seventh season, when he died during the filming of the final episodes. However, his character was included in the animated special, which was filmed in his honor. For storyline purposes, his character was recast with Ron Raines.