Jacob Eduard Mantius (18 January 1806 – 4 July 1874) was a German operatic tenor, composer and voice teacher.
Born in Schwerin, at the request of his father, a factory owner, Mantius began studying law at the University of Rostock in the autumn of 1826.
In 1829, he sang the tenor parts at a concert in Halle (Saale) conducted by Gasparo Spontini, the general music director of the Staatsoper Unter den Linden in Berlin.
In 1830, King Frederick William III of Prussia appointed him as a singer at his court opera.
After the end of his stage career in 1857, during which he appeared in 152 roles, he gave singing lessons and was also successful as a song composer.