Cecil Clyde Rousseau is a mathematician and author who specializes in graph theory and combinatorics. He is a professor at The University of Memphis and former chair of the USAMO.

Rousseau received his Ph.D. in 1968 from Texas A&M University.

He has an Erdős number of 1, and is among Erdős' top 10 co-authors.

To his students and colleagues, he's known affectionately as C²R.