Sextus P. Goddard was born around 1836 in Londonderry, Vermont, to Joseph B. Goddard and Lucy Lincoln. Her father probably died before 1850. The family eventually moved to Petersham, Massachusetts, and Goddard attended school there. He married Hannah M. Cutler in Gill, Massachusetts, on March 23, 1858.
Goddard worked as a farmer in Petersham, and by 1860, he owned $50 of real estate and $100 of personal property. He enlisted in the Union army on September 15, 1862, and mustered in as a private in Company F of the 53rd Massachusetts Infantry. He mustered out in Groton, Massachusetts, on September 2, 1863.
Hannah died in 1864, and Goddard married Mary Josephine Gates the following year. They had at least four children: Sextus, born around 1867; Mary, born around 1869; Mabel, born around 1873; Alice, born around 1875; and Malcolm, born around 1876. Hannah probably died in the late 1870s, and he married Mattie B. Hall on September 2, 1879. Goddard worked as a lumber dealer in Petersham. He died of “neuralgia of the heart” in Worcester, Massachusetts, on November 2, 1885.