Quirky cool Arlo is now well and truly back. Last year it broke into the US Top 200 boy names and consistently ranks among the most popular boy names on Nameberry. Along with its Irish and English roots, Arlo may be a shortened form of the Italian Carlo or the Spanish Carlos, both forms of Charles,and in Basque-speaking regions it is the word for area.

This spirited Gaelic classic, which became popular in Ireland via the illustrious twelfth century king Rory O'Connor, makes a highly energetic choice, now used for either sex. Rory's gender split is still trending boyward; it's one of the coolest boys' names starting with R.

Caleb is an attractive Old Testament name that has been in the US Top 100 for nearly three decades now. Consistently popular but never too popular, Caleb feels more like a classic than a momentary trend.

Isaac has shaved off his biblical beard and leaped into the upper echelon of popular boys' names, outrunning cousin Isaiah. A favorite of the Puritans, Isaac has never dipped below Number 400 on the US list of top boy names.

Jonah, the name of the Old Testament prophet who was swallowed by the whale, only to emerge unharmed three days later, is increasingly appreciated by parents looking for a biblical name less common than Jacob or Joshua, yet not too obscure. Plus, Jonah comes with a ready-made nursery-decorating motif.

Isaiah, like brethren Isaac and Elijah, is a once neglected biblical name now firmly back in favor, already surpassing such long-popular Old Testament stalwarts as Aaron and Adam. Isaiah has ranked on the US Top 1000 list for boys every year but two, 1969 and 1970.