Leroy Crockett was born on October 21, 1832, in Seneca County, Ohio, to Asa and Miriam Crockett. His father was a farmer who owned $7,000 of real estate by 1850. Crockett grew up in Adams, Ohio, and by 1850, he was working as a laborer. A decade later, he was working as a farmer, and he owned $12,770 of real estate and $7,827 of personal property.
On July 15, 1861, he received a commission as a 1st lieutenant in Company K of the 65th New York Infantry. Around December 1861, he was promoted to lieutenant colonel of the 72nd Ohio Infantry. Confederate forces captured in the Battle of Shiloh in April 1862. He was eventually exchanged, and he rejoined his regiment. He was promoted to colonel on November 29, 1862, and he died of disease in Seneca County, Ohio, on December 10, 1863.