Seyed Majid Hassanizadeh (born 1952) is a professor of hydrogeology at Utrecht University, where he heads the Hydrogeology group at the Faculty of Geosciences. His research focuses on flow of fluids and transport of solutes and colloids in porous media, through theory development, experimental studies, and modeling work. In particular, he focuses on two-phase flow, reactive transport in variably-saturated porous media, transport of micro-organisms, and biodegradation.