Hennessey is a distinctive girls' name in United States, ranking #9183 in 2014 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 2014, approximately 1 in every 148,828 girls born was named Hennessey. FALLING Recent data shows the name is currently falling.