Dagmar Johanne Amalie Overby (Danish: [ˈtɑwmɑ ˈɒwɐˌpyˀ]; 23 April 1887 – 6 May 1929) was a Danish serial killer. She murdered between 9 and 25 children, including one of her own, during a seven-year-period from 1913 to 1920. On 3 March 1921, she was sentenced to death in one of the most noted trials in Danish history—one that changed legislation on childcare.^[1] The sentence was later commuted to life in prison.

This article needs additional citations for verification. (January 2019)

Overbye was working as a professional child caretaker, caring for babies born outside of marriage, murdering her own charges. She strangled them, drowned them or burned them to death in her masonry heater. The corpses were either cremated, buried or hidden in the loft.

Overbye was convicted of nine murders, as there was insufficient proof of the others. Her lawyer based the case on Overbye being abused herself as a baby, but that did not impress the judge. She became one of the three women sentenced to death in Denmark in the 20th century, but she – like the other two – was reprieved.^{[citation needed]}

She died in prison on 6 May 1929, at age 42. Notes relating to her case are included in the Politihistorisk Museum (Museum of Police History) in Nørrebro, Copenhagen.

The Danish author Karen Søndergaard Koldste wrote a novel called Englemagersken (The Angel Maker) based on her.^[2] Teatret ved Sorte Hest in Copenhagen has performed a play named Historien om en Mo(r)der (Morder meaning "murderer" and moder meaning "mother") based on her life.

Overbye is a character in the 2024 film The Girl with the Needle, directed by Poland-based Swedish director Magnus von Horn, where she is portrayed by Trine Dyrholm, a candy shopkeeper who quietly advertises she can get babies adopted for a fee, but in fact kills them after their families drop them off.^[3][4] The film premiered at the 2024 Cannes Film Festival.^[4]

• List of serial killers by country
• List of serial killers by number of victims