Mitchell P. Rales (born August 1956) is an American billionaire businessman, investor, philanthropist, and art collector. He co-founded Danaher Corporation in 1984 with his brother Steven Rales, building it into a multinational conglomerate specializing in life sciences, diagnostics, environmental and applied solutions, with a market capitalization exceeding $180 billion. The Rales brothers also co-founded and expanded Estes Express Lines, a major less-than-truckload carrier. Rales has held significant roles in various companies, including serving as chairman of ESAB Corporation, a global leader in welding and cutting technologies. Additionally, he is a leading limited partner and co-owner of the National Football League's Washington Commanders, acquired in 2023 alongside a group including Josh Harris and David J. Blitzer.

Beyond business, Rales is renowned for his contributions to the arts. In 2006, he and his wife, Emily Wei Rales, established the Glenstone Foundation and Museum in Potomac, Maryland, which operates one of the most valuable private art collections in the world, featuring over 300 works of post-war and contemporary art displayed across a 300-acre campus. Rales previously served as president of the National Gallery of Art in Washington, D.C., from 2004 to 2007. His philanthropic efforts extend to education and health through the Rales Foundation, supporting initiatives in underserved communities.

Rales maintains a low public profile but wields considerable influence in business and cultural networks. His estimated net worth stands at approximately $4 billion as of 2025, primarily from his stakes in Danaher and other holdings, though some estimates place it higher at over $6 billion. He resides in the Washington, D.C. area and continues to shape industries through strategic investments and board positions.