Hennessey is a distinctive girls' name in United States, ranking #8413 in 2006 with 14 recorded births. The name reached its all-time peak in 2015 with 27 births ranking #5037. Since 1996, the popularity has increased by 133.3%. In 2006, approximately 1 in every 135,791 girls born was named Hennessey. FALLING Recent data shows the name is currently falling.