Ottilie "Tillie" Klimek (born Otylia Gburek; 1876 – November 20, 1936) was a Polish American serial killer, active in Chicago.

"[5] She mocked Frank himself, greeting him in the morning by saying "It won't be long now," and "You'll be dying soon," and joking with neighbors that he had "two inches to live.

"[7] She even knitted her own mourning hat as she sat at his bedside (which she later wore to the trial), and asked for the landlady's permission to store a bargain coffin she'd found for sale in the basement.

Klimek said that, "I will get rid of him some other way," and claimed that Nellie had given her a "goodly portion" of a poison called "Rough on Rats".

[12] The papers began to speak of Klimek not as a solo murderer, but as the "high priestess" of a "Bluebeard clique" in Chicago's Little Poland neighborhood.

Reporters noted that unlike most of the husband-killers who had been acquitted in Chicago courts, Klimek was not beautiful or charming, but a "squat" woman who spoke only broken English, despite having lived in the country since infancy.

[10] Klimek died in prison at Joliet Correctional Center on November 20, 1936, and was interred at the Bohemian National Cemetery in Chicago.