Ernst Octavianus Moltzer (1 May 1910 – 15 November 1941) was a sailor from the Netherlands, who represented his native country as at the 1936 Summer Olympics in Kiel. Ernst, as crew member on the Dutch 6 Metre "De Ruyter", took the 8th place with helmsman Joop Carp and fellow crew members: Ansco Dokkum, Kees Jonker and Herman Looman.