Lajos Szilassi (born 1942 in Szentes, Hungary) is a Hungarian mathematician and college professor, with research in the area of geometry, including projective and non-Euclidean geometry.
The Szilassi polyhedron is named after him.
It is a toroidal polyhedron with seven hexagonal faces, each pair of which share an edge; he published a paper describing it in 1986.