Terrence Thomas Kevin O'Leary (born July 9, 1954), also known as Mr. Wonderful, is a Canadian businessman and television personality. From 2004 to 2014, he appeared on various Canadian television shows, including the business news programs SqueezePlay and The Lang and O'Leary Exchange, as well as the Canadian reality television shows Dragons' Den and Redemption Inc. In 2008, he appeared on Discovery Channel's Project Earth. Since 2009, he has appeared on Shark Tank, the American version of Dragons' Den.

O'Leary co-founded SoftKey Software Products, a technology company that sold software geared toward family education and entertainment. During the late 1980s and 1990s, SoftKey became a major consolidator in the global educational software market, having acquired rival companies via hostile takeover bids, such as Compton's New Media, the Learning Company, and Broderbund. SoftKey later changed its name to The Learning Company and was acquired by Mattel in 1999, surprising many financial observers, who viewed O'Leary's company as a house of cards. Nevertheless the sale netted O'Leary around six million dollars. Mattel promptly fired O'Leary. The acquisition resulted in significant losses for The Learning Company and sparked multiple shareholder lawsuits targeting O'Leary's mismanagement.

In 2017, he campaigned to be the leader of the Conservative Party of Canada. He dropped out in April 2017, one month before the election, citing a lack of support in Quebec.

In addition to his native Canadian citizenship, O'Leary also holds Irish and Emirati citizenship.

O'Leary was born on 9 July 1954, in Montreal, one of two sons of Georgette (née Bookalam; Arabic: جورجيت بوكلام), a small-business owner and investor of Lebanese descent, and Terry O'Leary, a salesman of Irish descent. Kevin also has a brother, Shane O'Leary. Due to his paternal heritage, O'Leary also holds Irish citizenship and carries an Irish passport. O'Leary has dyslexia, which he argued helped him in the world of business.

O'Leary grew up in Mount Royal, Quebec. His parents divorced when he was a child, largely due to his father's alcoholism. His father died shortly after that, when O'Leary was only seven. After his father's death, his mother ran the family's clothing business as an executive. His mother later married an economist, George Kanawaty, who worked with the UN's International Labour Organization. His stepfather's international assignments caused the family to move frequently, and O'Leary lived in many places while growing up, including Cambodia, Ethiopia, Tunisia, and Cyprus. In his youth, he met both Haile Selassie of Ethiopia and Pol Pot of Cambodia. O'Leary attended Stanstead College and St. George's School, both in Quebec.

O'Leary's mother was a skilled investor, investing a third of her weekly paycheque in large-cap, dividend-paying stocks and interest-bearing bonds, ultimately achieving high returns in her investment portfolio. She kept her investment portfolio secret, so O'Leary only discovered his mother's skill as an investor after her death when her will was executed. Many of his investment lessons came from his mother, including the admonition to save one-third of his money.

O'Leary had aspired to become a photographer, but on the advice of his stepfather who prompted the young Kevin to be more realistic with his future career aspirations, ultimately led him to attend university, where he continued to develop his interest in business and investing since his youth. He received an honours bachelor's degree in environmental studies and psychology from the University of Waterloo in 1977 and an MBA in entrepreneurship from Ivey Business School at the University of Western Ontario in 1980.