Charles Coffin Sims is an American mathematician best known for his work in group theory. Together with Donald G. Higman he discovered the Higman–Sims group, one of the sporadic groups. The permutation group software developed by Sims also led to the proof of existence of the Lyons group (also known as Lyons–Sims group) and O'Nan group (also known as O'Nan–Sims group).
Sims was a student of John Thompson and received Ph.D. from Harvard University in 1963. In his thesis he enumerated p-groups, giving sharp asymptotic upper and lower bounds. Sims is one of the founders of computational group theory and is the eponym of the Schreier–Sims algorithm. He was a faculty member at the Department of Mathematics at Rutgers University from 1965 to 2007. During that period he had served, in particular, as Department Chair (1982–84) and Associate Provost for Computer Planning (1984–87). Sims retired from Rutgers in 2007 and currently resides in St. Petersburg, Florida.
In 2012 he became a fellow of the American Mathematical Society.