Hennessey is a distinctive girls' name in United States, ranking #8596 in 2020 with 12 recorded births. The name reached its all-time peak in 2015 with 27 births ranking #5037. Since 1996, the popularity has increased by 100.0%. In 2020, approximately 1 in every 134,626 girls born was named Hennessey. FALLING Recent data shows the name is currently falling.