Riordan is a distinctive boys' name in United States, ranking #7918 in 2015 with 10 recorded births. This places Riordan in the bottom 44% of ranked US boys' names for the year. Its actual usage is classified as Rare. The name reached its all-time peak in 2013 with 18 births ranking #5127. In 2015, approximately 1 in every 191,626 boys born was named Riordan. STABLE Recent data shows the name is currently stable.