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.

Ernst Moltzer married in 1939 with countess Gertrude Anna Luise Therese Thusnelde von Sarnthein from Austria.

[citation needed] During World War 2, he, along with his nephew and his uncle, was on the board of directors of Lucas Bols, a family-run company making and selling liquor, but was forced out after complaining that they were making too much money doing business with the German occupier.

[citation needed] A jawbone, fished out of the North Sea in 2003, was confirmed in 2024 to be Moltzer's.