Donald Wayne Riegle Jr. (born February 4, 1938) was a U.S. statesman from Michigan, serving as both as U.S. Representative and U.S. Senator. He was one of the Keating Five, senators who were investigated as part of a Savings and Loan scandal in the 1980s. His father, Donald W. Riegle, was mayor of Flint, Michigan.

He was born in Flint, Michigan and attended public schools there. He then attended Flint Junior College and Western University before graduating from the University of Michigan in 1960. He received a graduate degree from Michigan State University in 1961 and attended the Harvard Business School. He was a businessman and faculty member at Michigan State University, Boston University, and Harvard University.

He was elected as a Republican U.S. Representative in 1966 and was reelected three times. In 1973, he changed party affiliation to become a Democrat and was reelected as U.S. Representative in 1974. He did not run for reelection to the House, but was elected to the U.S. Senate in 1976 for the term commencing January 3, 1977. On December 30, 1976, before the new term began, he resigned from the House and was appointed by the Governor to fill the vacancy caused by the death of Senator Philip A. Hart for the term ending January 3, 1977. He was reelected to the Senate in 1982 and 1988. He did not seek reelection in 1994.

He was chairman of the U.S. Senate Committee on Banking, Housing and Urban Affairs, 1989-1995. He was a member of the U.S. Senate Committee on Budget from 1979-1994.

In 1995, he joined Weber Shandwick Public Affairs in Washington, D.C., serving as executive committee chair. He has been an adjunct professor at Michigan State University School of Business since 1995. He also serves as a senior strategist for business and finance with APCO Worldwide.

This article incorporates facts obtained from the public domain Biographical Directory of the United States Congress.