Hennessey is a distinctive girls' name in United States, ranking #9195 in 2007 with 13 recorded births. The name reached its all-time peak in 2015 with 27 births ranking #5037. Since 1996, the popularity has increased by 116.7%. In 2007, approximately 1 in every 147,881 girls born was named Hennessey. FALLING Recent data shows the name is currently falling.