Otis was born near Marietta, Ohio, on February 10, 1837, the son of Stephen and Sara Otis. His father was from Vermont and his mother, a native of Nova Scotia, Canada, came to Ohio from Boston, Massachusetts, with her family. The young Otis received schooling until he was fourteen, when he became a printer's apprentice. Otis and Eliza Ann Wetherby were married in Lowell, Ohio, on September 11, 1859, and they had three daughters, Lillian Otis McPherson, Marian Otis Chandler, who was secretary of Times-Mirror, and Mabel Otis Booth.