Theresa Tam (; born 1965) is a Canadian physician and public servant who served as the chief public health officer of Canada (CPHO), the second-in-command of the Public Health Agency of Canada (PHAC). Tam initially took the role as acting CPHO following the retirement of her predecessor, Gregory Taylor, on December 16, 2016. She was formally appointed on June 26, 2017. She stepped down as CPHO on June 20, 2025.