John Bernard 'Jack' O'Reilly Jr. (born September 21, 1948; died January 1, 2025) was an American Democratic politician and career public servant in Michigan's Wayne County. He served as the sixth mayor of Dearborn, Michigan, from 2007 until his retirement in 2022 after 15 years in office. Prior to becoming mayor, he represented Ward 3 on the Dearborn City Council from 1990 to 2007. O'Reilly focused on the diverse community of Dearborn, which has one of the largest Arab-American populations in the United States, emphasizing municipal issues including economic development, public safety, community relations, fiscal responsibility, and infrastructure improvements. Throughout his tenure, he navigated various local controversies, including initially defending the 2010 arrests of Wood and Qureshi amid debates over law enforcement practices, earning recognition as a steady hand in Dearborn politics. He did not seek re-election in 2022, passing the baton to a new administration, and left a legacy as a dedicated leader in local government.