Johann Gustav Wilhelm Moritz Heckscher (born 26 December 1797 in Hamburg; died 7 April 1865 in Vienna) was a German politician.
He served during the War of 1815 as a volunteer in the Hanseatic Corps, and then studied at the universities of Göttingen and Heidelberg. Upon completing his studies he settled in Hamburg, where he practiced law, and, after 1840, directed the politics of the Hamburger Nachrichten. In 1848 he was elected to the Vorparlament, in which he opposed the propositions of the Democratic Party. In the Frankfort Parliament proper (1848-49) he was at first a member of the left center, but inclined more and more to identify himself with the right. He advocated the election of Archduke John of Austria as vicar of the provisional national government (Reichsverweser), in which he himself was appointed minister of justice, and opposed the proposition to exclude Austria and erect a German empire with a Prussian king as hereditary emperor. Later he helped to organize the Pan-German Party.