Sergeant Reznik known simply as Reznik was an officer of Camp Haven under the command of Vosch. He was the senior drill instructor of the camp, tasked with training the new "recruits". Reznik is notorious in the camp for hard training regiments and slurs against the recruits. Reznik can best be described as a 'hard ass'. It is the dream of many of the squads of the camp to kill Reznik.
Reznik is secretly one of the Others and is a silencer, part of the 4th Wave. He was a human that was enhanced by The Others and was manipulated into thinking that he had another life outside possessing a human being when he truly was human all along.
Reznik only appears in The 5th Wave.
Maria Bello portrays Reznik in the film adaptation of The 5th Wave thus changing Reznik's gender to that of a woman.
Squad 53's prime squad commander and trainer. Ben did not like Reznik and in turn he was particularly hard on him. When Sam Sullivan/Nugget came to Camp Haven and was brought into the squad Reznik made a point to be particularly hard on him. Ben Parish came to his defense and spoke up against him. Reznik then rounded on Ben in front of everyone but Ben stayed firm in his defense of Sam. For not backing down Reznik had him replace Flintstone as Squad 53's squad leader. When Ringer was introduced into the squad Reznik was making it harder for Ben to do his mandatory pushups.
When Squad 53 was given their first real combat assignment, Reznik was there to supervise them. He had a sniper rifle in hand and shot at them in order to motivate them to see if they would perform in combat conditions. He had a monitoring device which had their locations due to their trackers. He was pinned down by return fire from Poundcake.
However, unbeknownst to him, Ringer was realizing the truth about Camp Haven and about all the leaders and adult soldiers there. She had removed her tracker and Ben's monitoring eyepiece had her lighting green as soon as she did. That got him to remove his and they went to confront the sniper. Since they had cut out their trackers he didn't realize they were coming. Ringer shot him and they were surprised to see that it was Reznik.
When Ben infiltrated Camp Haven to get Nugget back, he told Vosch that Flintstone and Ringer had killed Reznik because they had gone Dorothy. He claimed that he had guessed Reznik was there to see if they were ready for combat situations but was ready to terminate them if they went Dorothy which Vosch highly doubted.
- The name "Reznik" is derived from the Czech word "řezník" meaning "butcher". "Řezník" is also a Czech and Slovak surname.
- In the film, Reznik's death was altered. She was strangled to death by Cassie when she was being screened. Her uniform was used by Cassie as a disguise. In a deleted scene, Reznik's death matched that of the character Dr. Pam. Cassie knocked her out and took out her tracker and put it in her nose. When Reznik came to her senses, she tried to activate its kill function but ended up shocking herself.