Isaac Leopold Rice (February 22, 1850 – November 2, 1915) was a German-born American businessman, investor, musicologist, author, and chess patron. As part of a successful career in the manufacturing industry, in 1899 he acquired the Holland Torpedo Boat Company, which was renamed the Electric Boat Company and produced submarines for the U.S. and British navies. It continues today as General Dynamics Electric Boat.

Rice was born in Wachenheim, Bavaria in 1850, the son of Mayer Rice and Fanny Sohn Rice. He emigrated to the United States with his mother in 1856. He was educated at the Central High School in Philadelphia and at nineteen he was sent to Paris, where he studied music for three years. While there he sent stories to the Philadelphia newspapers for printing. In 1868 he moved to England, where he became a teacher of music and languages. On his return to America a year later he moved to New York City and practiced music before going back to school to become a lawyer. After graduating from Columbia College Law School in 1880 he practiced law for the rest of the decade.

In the practice of law he became more aware of and involved in the transportation business, mainly in the expanding railroad empires and their multiplying legal imbroglios. He was regarded in his time as one of the ablest specialists in railroad law in the United States, and held large investments in several lines, including the Philadelphia and Reading Railroad and Reading Railroad.

He was invited to start a publishing company by some associates in the music printing societies. In the 1890s he was looking to move and diversify and possibly invest early in emerging companies with a potential for growth. In 1892 he bailed out the bankrupt Electro-Dynamic Company in partnership with its proprietor, William Woodnut Griscom. He became the first president of The Forum magazine, and later the Electric Storage Battery Co. (later Exide) in 1897.

Some of the numerous other companies Rice organized or was involved in included the Electric Vehicle Company, Car Lighting and Power Company, American Casein Company, and the Consolidated Rubber Tire Company.

As president of Electric Storage, he became aware of the attempts (despite financial difficulties) since 1896 to deliver the first modern submarines for the US Navy, which ran on electric power while underwater. A year after the 1897 launch of their first vessel, the Holland VI, the management of John Philip Holland and Lewis Nixon (owner of the Crescent Shipyard in New Jersey, where Holland VI was built) found it difficult to finish making the last details operable and were running out of cash. Isaac Rice moved in, taking over and renaming the company as the Electric Boat Company on 7 February 1899. After a few months of negotiations and multiple tests, the United States Navy purchased Holland VI, renamed it USS Holland, and awarded the new company a contract to build its first fleet of Plunger-class submarines. Also in 1899, Rice added the Electric Launch Company (Elco) to his family of companies.

During World War I, Electric Boat and its subsidiaries, notably Elco, built 85 Navy submarines and 722 submarine chasers, along with 580 motor launches for the British Royal Navy (in the World War I era Electric Boat's submarines were built by subcontractors, primarily Fore River Shipbuilding in Quincy, Massachusetts). Electric Boat was a founding company of General Dynamics Corporation, which is the company's Cold War progeny.

In 1902 he received from Bates College the honorary degree of LL.D.