Catherine O'Leary (also known as Cate O'Leary; ca. 1827 – 3 July 1895) was an Irish immigrant living in Chicago, Illinois in the 1870s who became famous when it was alleged that an accident involving her cow had started the Great Chicago Fire of 1871.
She was married to Patrick O'Leary. The couple's son, James Patrick O'Leary, grew up to run a Chicago gambling hall.
Chicago fire 
On the evening of October 8, 1871, a fire consumed the O'Leary family's barn at 137 DeKoven Street. Due to a high wind and dry conditions it spread to burn a large percentage of the city, an event known as the Great Chicago Fire.
After the Great Fire, Chicago Tribune reporter Michael Ahern published the story that the fire started when a cow kicked over a lantern while a woman was milking it. Though the woman was not named in the original report, Mrs O'Leary was soon identified, since her barn had been the source. Various illustrations and caricatures soon circulated depicting Mrs O'Leary with the cow. The story took the population's imagination and is still widely circulated.
Ahern admitted in 1893 that he had made the story up because he thought it would make colorful copy. The official report at the time stated "whether it originated from a spark blown from a chimney on that windy night, or was set on fire by human agency, we are unable to determine". Mrs O'Leary herself stated that she was in bed when the fire started, and had no knowledge of what set it off. Daniel "Pegleg" Sullivan, who was the first person to raise the alarm, reported that on seeing a fire in the barn, he ran across the street to free the animals (which included a cow owned by Sullivan's mother). He then informed the O'Learys, who were at home.
Anti-Irish attitudes at the time encouraged stories scapegoating the O'Leary family. It was claimed that the supposed accident happened because she was drunk, or that she hid the evidence to avoid being blamed. Neighbors later claimed to have seen shards from the broken lamp, but none of these stories could be verified. One person stated that he had found the lamp, but it had been stolen by an Irishman to protect the O'Learys.
Other theories posit that Daniel "Pegleg" Sullivan himself may have started the fire, or Louis M. Cohn, who later claimed to have been gambling in the barn with the O'Learys' son and several other boys.
Death and aftermath 
Catherine O'Leary died on July 3, 1895 of acute pneumonia at her home at 5133 Halsted Street and was buried at Mount Olivet Cemetery. In the PBS documentary, Chicago: City of the Century, a descendant of O'Leary stated that she spent the rest of her life in the public eye, in which she was constantly blamed for starting the fire. Overcome with much sadness and regret, she "died heartbroken."
Amateur historian Richard Bales was able to garner enough evidence on Sullivan to convince the Chicago City Council to exonerate O'Leary of all guilt in 1997.
Cultural references 
The story of Mrs. O'Leary's Cow has garnered the attention and imagination of generations as the cause of the fire. Popular culture, such as Gary Larson's cartoon The Far Side, Brian Wilson's song "Mrs. O'Leary's Cow", the song "The Chicken or the Egg" from The Easter Bunny Is Comin' To Town, and Rita Hayworth's song "Put the Blame on Mame" from the movie Gilda and even Quentin Tarantino's debut film Reservoir Dogs have referred to the story with the expectation that the populace will understand the reference.
Popular 1930s character actress Alice Brady won a Best Supporting Actress Oscar for her performance as Mrs. O'Leary in the film In Old Chicago, in which she is portrayed as a heroic figure. The film dramatizes a variant of the traditional story. She is helping her cow to suckle a new calf, but accidentally leaves the lantern behind when she departs in a hurry, after being told that one of her sons has been injured in a fight.
- Late one night, when we were all in bed,
- Old Mother Leary left a lantern in the shed;
- And when the cow kicked it over, she winked her eye and said,
- "There'll be a hot time in the old town, tonight."
- Pierce, Bessie Louise (1957, rep. 2007). A History of Chicago: Volume III: The Rise of a Modern City, 1871–1893. Chicago: University of Chicago Press. p. 4. ISBN 978-0-226-66842-0.
- L.L. Owens, The Great Chicago Fire, ABDO, p. 7.
- "The O'Leary Legend". Chicago History Museum. Archived from the original on 2011-01-11. Retrieved 2007-03-18.
- Obituary, Chicago Tribune, July 4, 1895, p.1.
- Edmonds, Molly. "Did the Great Chicago Fire really start with Mrs. O'Leary's cow?". HowStuffWorks. Retrieved 2011-10-07.