Samuel "Sam" Zell (born September 1941) is a U.S.-born billionaire and real estate entrepreneur. He is co-founder and Chairman of Equity Group Investments, a private investment firm. With an estimated net worth of US$3 billion, he is ranked as the 68th richest American by Forbes. In April 2007, Zell completed a leveraged buyout of the Tribune Company, publisher of the Chicago Tribune and the Los Angeles Times. He is also the owner of the Chicago Cubs.

Zell was born in Chicago in 1941 to Jewish immigrant parents from Poland who fled the country just before the Nazi invasion in 1939. Shortly after moving from Seattle to Chicago, Zell's father Bernard changed the family name from Zielonka to Zell. He received his BA (1963) from the University of Michigan, where he was a member of the Alpha Epsilon Pi fraternity. He also received his JD (1966) from the University of Michigan Law School.

Zell, with Robert H. Lurie went on to found the Equity Group Investments, LLC, which spawned three real estate public companies, including: Equity Residential, the largest apartment owner in the United States; Equity Office Properties, the largest office owner in the country; and Manufactured Home Communities, a mobile home company. In addition, Zell has created a number of public and private companies. He also controls SZ Investments LLC as his investment arm.