The Most Infamous Irish Mobsters of All Time

Who are the most infamous Irish mobsters in US history? Narrowing down a list isn't easy. From Chicago to Boston to Philadelphia, Irish mobsters have controlled everything from bootlegging (during Prohibition years) to horse racing, and everything in between. From Bulger to Spillane, check out this list of infamous Irish mob members ordered from earliest to most recent, and learn how these mob kings rose to infamy. Not surprisingly, they were only one small part of the much larger US gangster ring.


  • 1

    James 'Big Jim' O'Leary

    James 'Big Jim' O'Leary
    Photo: John R. Chapin / Wikimedia Commons / Public Domain

    Big Jim O'Leary was a powerful Irish mob boss in Chicago for more than a decade, controlling gambling on the city's South Side with an iron fist.

    His criminal career started as a teenager, when O'Leary worked for bookies in Long Beach, Indiana. He later began operating his own illegal gambling ring on the steamship The City of Traverse on Lake Michigan. Both of these early operations failed to gain traction, largely because of O'Leary's refusal to pay off local police. He only found financial success following the passing of Chicago crime lord Michael Cassius MacDonald, which led to O'Leary's assuming control of gambling on Chicago's South Side in the 1890s.

    And yes, if the O'Leary/Chicago connection seems familiar, it should: Big Jim's parents, Patrick and Catherine O'Leary, owned the barn where the infamous Great Chicago Fire of 1871 is thought to have started. Though it's never been proven, their cow was supposedly the arsonist responsible.

  • John Patrick Looney
    Photo: Pinkerton Detective Agency / Wikimedia Commons / Public Domain

    A surprisingly educated and sophisticated gangland figure, John Patrick Looney was admitted to the Illinois Bar in 1889, was active in Democratic Party politics, and started his own newspaper - the Rock Island News of Rock Island, Illinois - in 1905. He would go on to use the publication to extort powerful local residents (threatening to publish unflattering stories unless he received a payoff) and to attack other personal enemies. Looney eventually sold his stake in the paper in 1908, though he continued to harass and threaten the purchaser - W.W. Wilmerton - who had hoped to dismantle it. (He even had a duel with Wilmerton at one point, during which Looney was wounded.)

    During and following his tenure at the Rock Island News, Looney got involved in gambling and the escort business in addition to his extortion ring. Once Prohibition became the law of the land, he extended his enterprise into the protection racket, as well, offering cover for law violators.

    In 1922, his fortunes changed after Looney allegedly ended William Gabel, a man who had provided evidence against Looney to Prohibition agents. In retaliation, Looney's son was taken out by rivals, and police raids shut down his speakeasies and brothels. Though he fled, first to Canada and then New Mexico, Looney was eventually apprehended, and was convicted of Gabel's demise, as well as "conspiracy to protect gambling, prostitution and illicit liquor traffic." He was sentenced to 14 years behind bars. He perished in 1947 in a tuberculosis sanitarium.

    Looney is the inspiration for Paul Newman's character, John Rooney, in the Oscar-winning 2002 movie Road to Perdition. The character was originally named "John Looney" in Max Allan Collins's graphic novel of the same name.

  • Dean O'Banion
    Photo: Unknown / Wikipedia / Public Domain

    Dean O'Banion (sometimes referred to as Dion O'Banion) was a native of Chicago's North Side neighborhood and, during the beginning of the Prohibition era, united with Italian South Side mobsters (including boss "Papa" Johnny Torrio and his associate, Al Capone) to ramp up their bootlegging operations and avoid turf battles. In 1924, O'Banion decided to break with his former partners, and unsuccessfully attempted to frame Torrio, leading to a bloody struggle for the control of North Side bootlegging.

    In November 1924, O'Banion was slain while working in his flower shop. The misdeed started a gruesome five-year Chicago turf war that culminated in the infamous St. Valentine's Day Massacre of 1929.

    O'Banion was the basis for the character played by Jimmy Cagney in the 1931 film The Public Enemy.

  • 4

    George 'Bugs' Moran

    "Bugs" Moran was a gangster during the Prohibition era in Chicago. After embarking on a criminal career as a teenager, he gained a reputation as a lunatic with a ferocious temper, earning the nickname "Bugs" (which, at the time, was slang for "crazy"). Before the age of 21, he had already been incarcerated three times.

    During Prohibition, Moran found his own bootlegging operation in direct competition with the Chicago Italian family set up by Al Capone, triggering a turf war (and lifelong rivalry) between the two men. Their back-and-forth series of attacks and retaliations lasted through the rest of the Prohibition era, and led Moran to popularize the technique of driving by Capone's properties and peppering them with gunfire, an iconic image of organized crime from the era and the inspiration behind "drive-by shooting."

    Moran was convicted of robbing a bank messenger in Ohio in 1946, and spent most of the remainder of his life behind bars. He perished destitute in 1957, mere weeks after beginning a new sentence for bank robbery.