Hennessey is a distinctive girls' name in United States, ranking #8785 in 2000 with 11 recorded births. The name reached its all-time peak in 2015 with 27 births ranking #5037. Since 1996, the popularity has increased by 83.3%. In 2000, approximately 1 in every 165,088 girls born was named Hennessey. FALLING Recent data shows the name is currently falling.