Mortimer Benjamin Zuckerman (born June 4, 1937, in Montreal, Quebec, Canada) is a Canadian-American billionaire real estate magnate and media proprietor, publisher, editor-in-chief, investor, and philanthropist of Ashkenazi Jewish descent. He immigrated to the United States for graduate studies after earning a Bachelor of Commerce (1957) and MBA (1958) from McGill University, followed by a Master in City Planning from Harvard University (1961). Zuckerman began his career as an associate professor of city and regional planning at Harvard Graduate School of Design and a lecturer at Yale University. In 1964, he co-founded Boston Properties, serving as its executive chairman and former CEO, transforming it into one of the largest real estate investment trusts in the United States with a focus on high-end commercial properties and office buildings in major metropolitan markets.

Zuckerman expanded into media ownership, acquiring U.S. News & World Report in 1984, where he remains owner, publisher, and editor-in-chief, transforming it into a leading news magazine focused on rankings and analysis; he frequently authored columns and served as a commentator on political and economic affairs, particularly regarding Middle Eastern relations and American fiscal policy. He previously owned and published the New York Daily News (1993-2017), The Atlantic (1980-1999), and Fast Company, showcasing his influence in American journalism and media ownership. His media ventures have emphasized investigative journalism and public policy coverage, often reflecting his centrist to liberal political leanings, including support for Democratic causes and involvement in foreign policy discussions, though he has maintained close ties to both Democratic and Republican administrations and criticized both major U.S. parties. He is a prominent pro-Israel advocate and reportedly relies on Hoenlein as an adviser on Jewish affairs, and he is a member of the Washington Institute for Near East Policy's (WINEP) Board of Advisors. He also served as Chairman of the Conference of Presidents of Major American Jewish Organizations from 2001 to 2003.

As a philanthropist, Zuckerman has served as past president of the Board of Trustees of the Dana-Farber Cancer Institute in Boston and is involved in various cultural and educational initiatives, with a recent focus on neuroscience and data science through massive gifts to Columbia University and other institutions. His contributions have earned him prestigious awards, including the Commandeur de l'Ordre des Arts et des Lettres from the French government, the Lifetime Achievement Award from Guild Hall, and the Gold Medal from the American Institute of Architects. Despite his vast success, his financial legacy was notably impacted by the Bernard Madoff Ponzi scheme, which affected his private charitable foundation; the foundation subsequently sued Merkin for losses incurred through Madoff investments. Divorced from art historian Marla Prather in 2001 after marrying in 1997, he has no publicly known children. As of August 2024, his net worth is estimated at US$2.6 billion, primarily from real estate and media holdings.

Throughout his career, Zuckerman has navigated controversies related to his media ownership, including criticisms over editorial decisions at the New York Daily News and debates on the commercialization of journalism at U.S. News & World Report. No major legal troubles or scandals are prominently documented, but his business dealings in real estate have occasionally drawn scrutiny for urban development impacts. He maintains a low public profile on personal matters.