The FAS offers well over two hundred courses dealing with topics related to ethnicity, race, and racism.
Freshman Seminars and Expository Writing classes are a good place for first-year students to start exploring these topics:
General Education courses provide another good introduction for students in any year of study:
Social Science departments and degree committees offer over one hundred courses exploring these topics in great depth.
Other courses that incorporate discussions of race, racism, ethnicity, and identity into their subject matter can be found scattered across departments, programs, and concentrations as distinct as English, History of Art & Architecture, Microbiology, Philosophy, and many others:
Even some language courses touch on these topics (list may be incomplete at this time [24 July 2020]).
Due to my.harvard search function limitations, a small number (~2%) of the search results may be irrelevant (e.g., a course on the "space race" in Astronomy).