When William Maulsby was born on 25 June 1774, in York, Pennsylvania, United States, his father, John Maulsby Senior, was 39 and his mother, Lydia John, was 28. He married Mary Cox on 17 April 1804, in Tennessee, United States. They were the parents of at least 2 sons. He died in 1806, in Ohio, United States, at the age of 32.