Alpheus Hyatt was born on April 5, 1838, in Washington, D.C.

He was an American zoologist and paleontologist. He briefly attended the Maryland Military Academy and Yale University, and after graduating from Harvard University in 1862, he enlisted in the Massachusetts Volunteer Infantry for the Civil War, emerging with the rank of captain. After the war, he worked at the Essex Institute (now the Peabody Essex Museum) in Salem, Massachusetts. He co-founded American Naturalist and served as its editor from 1867 to 1870. He became a professor of paleontology and zoology at the Massachusetts Institute of Technology in 1870, where he taught for eighteen years, and was a professor of biology and zoology at Boston University from 1877 until his death in 1902. He also served as curator of the Boston Society of Natural History. In 1875, he was elected a member of the National Academy of Sciences. In 1898, he received the honorary degree of LL.D. from Brown University.

In 1867, he married Audella "Della" Beebe (1840–1932). He died on January 15, 1902, in Cambridge, Massachusetts.