M. Brock Weir (1921–1996) was chairman and chief executive officer of Ameritrust Company. Born in Wenatchee, Washington, Weir served as an Army captain during World War II. He joined the National Bank of Commerce in Seattle in 1947 after earning a bachelor’s degree from the University of Washington. In 1963, having completed postgraduate studies at the Dartmouth Graduate School of Financial Management, Weir joined the San Francisco-based Bank of California as a vice president. He was the bank’s president before coming to Cleveland in 1973 to assume the post of president and chief executive of Cleveland Trust. The following year he became chairman and CEO of the bank’s holding company, CleveTrust Corporation, which later adopted the name Ameritrust. He was named chairman of the bank in 1978.

Weir served as a trustee of John Carroll University and on the advisory board of Notre Dame College. He was a board member of the Greater Cleveland Growth Association was involved with the United Way campaigns, the Society for Crippled Children and WVIZ/PBS. In 1983, he retired from Ameritrust and moved to California.