Sigurd Bernardus Angenent (born 1960) is a Dutch-born mathematician and professor at the University of Wisconsin–Madison. Angenent works on partial differential equations and dynamical systems, with his recent research focusing on heat equation and diffusion equation. The Angenent torus and Angenent ovals are special solutions to the mean curvature flow published by Angenent in 1992; the Angenent torus remains self-similar as it collapses to a point under the flow, and the Angenent ovals are the only compact ancient solutions other than circles for the curve-shortening flow.