Willem Theo "Wim" Grothuis (born 16 December 1944) is a retired Dutch rower.
He competed at the 1972 Summer Olympics in the coxed fours, together with Evert Kroes, Jan-Willem van Woudenberg, Johan ter Haar and Kees de Korver, and finished in seventh place.
His team finished ninth in this event at the 1971 European Championships.