Alexander J. Bache was an American physicist, chemist, and cartographer from Philadelphia. He was the great-grandson of Benjamin Franklin.

Bache was known for conducting detailed surveys of the American coastline. He was originally an army engineer and was behind the establishment of a number of coastal fortifications, including Fort Adams in Newport, Rhode Island. He later became Superintendent of the United States Coast Survey and built it up into one of the world’s most modern and efficient cartographic institutions in the years leading up to the Civil War.

During the Civil War, Bache spearheaded a monumental effort to compile and collate the latest survey data so that new and more accurate charts could be drawn to aid the war effort. Bache also worked as a professor of Chemistry and Natural Philosophy at the University of Pennsylvania.