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This article is about the Aleksander from Adam's world. For the Aleksander from Eva's world, see Aleksander Tiedemann. For the Aleksander from the original world, see Aleksander Köhler.

Aleksander Tiedemann (previously Aleksander Köhler, originally Boris Niewald) is the director of the Winden Nuclear Power Plant. He is married to Regina, with whom he has a son, Bartosz.



Boris Niewald arrives in Winden in 1986, apparently on the run. He encounters Ulrich Nielsen and Katharina Albers beating up Regina Tiedemann and scares them off by brandishing a gun. He gives Regina the name Aleksander, but Hannah Kahnwald later sees him burying a bag in the forest containing the gun and a passport with his photo and the name Boris Niewald issued in Gießen, swapping it for another issued in Marburg for an Alexander Köhler.[1]


By 2019, Aleksander is married to Regina and director of the power plant, a position once held by his mother-in-law Claudia. Hannah is his massage therapist.

On June 20, Aleksander's attention is piqued when he comes across the headline, "Murder in Marburg unsolved 33 years later. Search for two fugitive perps still on" while reading the newspaper. He ponders how an investigation can still be ongoing after more than three decades of searching.[4]

In November, after the disappearance of Mikkel, Ulrich finds a locked door in the cave that seemingly leads to the nearby nuclear power plant. He tells Charlotte to request a search warrant for the power plant. Aleksander blocks this and when Ulrich requests access he refuses him entry, citing security regulations. He also has things taken away before the police can find them.[5]

Hannah, having taken Aleksander's bag to their massage appointment, blackmails him with it. She demands no money, only the destruction of Ulrich's life. In turn, Aleksander calls his friend in the Winden Police, Torben Wöller, and tells him to dig up dirt on Ulrich. He also mentions that they will soon be able to return the barrels of waste, which had been stored on a truck.[1]


June 24[]

Inspector Clausen has gone to the nuclear power plant to question Aleksander. He tells him that he denied Ulrich Nielsen entry to the plant due to stricter security after the Fukushima disaster. He says the door to the caves was sealed shut in the 1980s as a security measure, so it would not be possible for someone to enter. Clausen tells him he finds it unusual that everyone who was born in Winden seems to remain there. Aleksander attributes this to the steady employment available at the power plant, although that will change soon. Clausen then points out that Aleksander is an exception, having come from somewhere else, arriving in 1986, around the time that Mads disappeared. Aleksander points out that he arrived several weeks after Mads' disappearance. Clausen then asks why he took his wife's last name, which was unusual at that time. Aleksander says that as Regina was an only child, they had wanted to preserve the name. He asks what his original name was. He tells him Köhler.

June 25[]

Regina reveals that Bartosz is missing. Regina asks Aleksander to tell her that everything is fine, but his answer is not convincing.

June 26[]

Clausen closes in on Aleksander, stating he is being charged for identity theft and obstruction. He says he is looking for Aleksander Köhler, who is his brother. He says he believes his height is different to what his documents state and curtly states "you are definitely not my brother."

June 27[]

Clausen hands Aleksander a search warrant for the Winden Nuclear Power Plant. He vows that even if he cannot prove that Aleksander murdered his brother, he will still get him for whatever is happening in Winden. Aleksander, distraught, begs Torben to help him and stop Clausen, but Torben says it is impossible, and perhaps things will be better now the truth is out.

2019 (Eva's World)[]

November 4[]

Alternate reality Charlotte comes to the plant and tries to get Aleksander to give her the schedules his employees had the night of Erik's disappearance. He asks if she has a court order, but Charlotte says she does not. Aleksander tells her he will have the schedules sent to her. Charlotte asks how he has been, and Aleksander replies he is alright. On her way out Charlotte wonders if it was possible for Erik to have made his way onto the grounds. Aleksander responds that this is impossible because the access points were sealed years ago. He then glances over the photograph of his wife Regina, who had passed away.

November 5[]

Hannah visits Aleksander and says sorry about what happened to Regina. She asks Aleksander how he and Bartosz are doing and tells him she wants to offer him a deal, telling him she has something that was his and wanted to return it. She brings out a bag, and asks him if he remembers it, Seeing Aleksander's worried face, Hannah tells him that the contents of the bag were safe. Aleksander asks if what she wants is money, but she refuses because she wants Charlotte "destroyed" and to lose everything.

November 7[]

Charlotte visits Aleksander Tiedemann in order to ask him some questions regarding Mads Nielsen in the bunker. When asked if he was okay, Aleksander mentions everybody is stressed because of the plant's demolition. He looks at the bag Hannah had given him when she blackmailed him into ruining Charlotte. Charlotte asks him when he had gotten to Winden, and he tells her that in fall in 1986 and also started working at the plant around that time. He asks her if the shift schedules he had sent had gotten to her, and she nods. She also asks if previous shift schedules at the plant had been archived to which Aleksander responds that they had and wondered what month. However, Charlotte did not want to find a month, she wanted information for 1986.

November 8[]

With six hours left until the apocalypse, Aleksander asks where the containers are and tells Obendorf to do as he says. Bartosz walks in and asks his father if everything is okay, and Aleksander tells him he would have to leave despite having promised he would stay. He tells Bartosz he is being blackmailed using a murder in Marburg which had happened 33 years ago, mentioning there were decisions in life that could never be undone. He confesses his name is not Aleksander, but Boris Niewald, and begs Bartosz to believe he is not a murderer. Bartosz asks if Regina knew about it, and Aleksander shakes his head. Aleksander tells Bartosz that his mother is the best thing that had ever happened to him, and tries to hug him, but his son turns away and leaves.

Later, Bartosz calls his father to warn him about the barrels, but he doesn't answer the phone. Aleksander calls Charlotte instead and asks her to come to the plant. Aleksander brings Charlotte inside the room where the containers were in, and opens one which has a dark substance which starts to rise, and forms the God Particle, triggering the apocalypse.

Original World[]

While Aleksander/Boris still exists in the Original World because he wasn't born from time travel, he didn't meet and marry Regina and have a son with her.


Season 1[]

Season 2[]

Season 3[]


→ See 40 images of Aleksander Tiedemann at Images of Aleksander Tiedemann.


  1. 1.0 1.1 1.2 Dark Season 1 Episode 9: "Everything Is Now"
  2. Dark Season 2 Episode 1: "Beginnings and Endings"
  3. Dark Season 3 Episode 8: "The Paradise"
  4. Dark Season 2 Episode 6: "An Endless Cycle"
  5. Dark Season 1 Episode 2: "Lies"