At the heart of NBC drama The Blacklist is a list of blacklisters, high-profile criminals that the FBI has been searching for or, in some cases, doesn't even know exists. Career criminal Raymond Reddington has struck a deal to deliver these blacklisters one by one in exchange for his freedom. His motives are questionable, as the FBI discovers that he's turning these people in order to expend his own empire. Nonetheless, the reward of taking down some of the most notorious and dangerous criminals is too sweet to resist.

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Who are the Blacklisters? They are people who do heinous things, often with a special set of skills that make them highly sought-after in the criminal underworld. The list includes well-known characters like Tom Keen, Dembe Zuma, Kathryn Nemec (a.k.a. Mr. Kaplan), and Katarina Rostova. But over the last seven seasons, many other Blacklisters have been revealed. Here are some of the most memorable ones.

Robert Vesco (No. 9)

He's one of the most memorable because he was Raymond's mentor and the only person to successfully double-cross him. After stealing $200 million from a mutual fund, he faked his own death, fled, and lived in hiding for a decade.

But not before he stole Red's entire life savings, assuring him he was investing in a cattle ranch that was actually a brothel. In the end, Red finally got his revenge on the man, proving that he was the superior criminal.

Ian Garvey (No. 13)

With his signature look including a bald-shaven head and dark-rimmed glasses, Garvey was a blacklister who was masquerading as one of the good guys. As a high-ranking US Marshal, he was secretly involved with the Nash Syndicate drug cartel.

He was also a surrogate father to Red's biological daughter Jennifer and the person responsible for Tom Keen's death. A highly dangerous force against Raymond given his position and the fact that he knew the truth about those bones, Garvey was one of the biggest threats. But he was eventually eliminated.

Constantin Rostov (No. 14)

Otherwise known as Alexander Kirk, Rostov, a former KGB agent, believed that Elizabeth was his biological daughter. Married to her mother Katarina, he sought out Elizabeth in hopes that she could help him with blood transfusions he needed to treat a rare blood disorder.

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With deep pockets and plenty of connections, Rostov seems as much in the dark about the truth of the past as Liz. In the end, Red lets him go and his fate is unknown. Though it is assumed that without the transfusions he needed, he may have died.

Sharon Fulton (No. 19)

Clever and manipulative, Fulton is a psychiatrist who pays for the families of the victims of serial killers to get counseling. It seems like she's trying to do good deeds. But in reality, she uses her knowledge and skills in forensic psychiatry and criminology to track killers who escape justice and have them killed.

The vigilante killer doesn't commit murder herself but has corrupt federal agents do it for her, making sure they kill the person in the same way they killed their victims.

Bogdan Ivanovich Krilov (No. 29)

This medical doctor has a very unique skill: he can manipulate people by making them believe false memories or erase their memories altogether. Naturally, his skills were in high demand on the black market, especially for the purposes of erasing the memories of witnesses to crimes.

His job became personal when he used his talents to erase Liz's memories about the night of the fire when her father died. In season 7, Red had Krilov released in order to help him find Ilya Koslov where, in an ironic twist of fate, Krilov's memory was erased before going back to prison.

Hans Koehler (No. 33)

A black market plastic surgeon, Koehler is the man responsible for changing Red's physical appearance and thus hiding his real identity. And thus, he's also one of very few people who knows who he really is.

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More than 30 years ago, Koehler performed facial reconstruction on Raymond so that he could become Mr. Reddington. His real identity remains a mystery. And Koehler will never be the one to reveal it since he is now dead, killed by Bastien Moreau, an international assassin.

Bo Chang (No. 38)

Chang doesn't commit murder or hunt down enemies. What makes him particularly dangerous, however, is that he can cause chaos from behind a computer screen. An Internet expert known as the Troll Farmer, he is skilled in information, cyber, and psychological warfare.

He can use the Internet to stage events, make fake accounts, and doctor photos to spread disinformation that will serve his clients. He's essentially a specialist in creating very convincing fake news stories that can have a far-reaching, critical impact. It has been said that he triggered an Ebola scare in Atlanta to help raise the stock value of a drug company and covered up an art heist in Paris via a fake terrorist attack.

Raleigh Sinclair III (No. 51)

One of the most fascinating Blacklisters, Sinclair would help guilty people fake alibis through intricate plans that involved finding and threatening doubles to pose as them. He would train the double in a routine for weeks or months before the crime was committed.

He would then create masks that look like his clients and have the doubles act like them, going about the usual routine, while the real person secretly committed the crime. When the job was done, Sinclair would then have the double murdered. Essentially, he helped people commit perfect murders.

Asa Hightower (No. 59)

Known as the Apothecary, Hightower was a skilled chemist who knew how to manufacture custom-made poisons designed for specific people. He would be given a target and could create a special poison just for them.

The poisons would do things like cause an aneurysm or overdose. But what was most impressive was that they leveraged conditions or weaknesses the people already had so the deaths always looked natural or accidental. There was no way to detect the poison after the fact.

Thelonious Prackett (No. 151)

One of the most disturbing scenarios on the series, Prackett served as the organizer of the Les Fleurs Du Mal secret society of bored billionaires. Looking for thrills that usually can't be bought with money, these people fell right into Prackett's sinister plan.

His events would involve one participant being randomly selected as a victim who had to escape a deadly trap while everyone else looked on. The belief is that the person has a chance to escape, but really they don't. Eventually, they die in spectacular fashion as the guests morbidly respond with cheers.

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