Leo is a strong-yet-friendly name that was common among the Romans, used for fourteen popes, and is now at its highest point ever in the US thanks in part to Leonardo "Leo" DiCaprio.

Sebastian is an ancient martyr's name turned literary, and Little Mermaid hero—think Sebastian the Crab—that's more popular than ever, as a classic-yet-unconventional compatriot for fellow British favorites T Theodore and Oliver.

For centuries this name was associated primarily with the towering figure of Italian Renaissance painter-scientist-inventor Leonardo da Vinci, and was scarcely used outside the Latin culture.

It wasn't so long ago that Romeo was considered as outre for an American baby as Casanova or Cupid. But that really changed when David and Victoria Beckham chose it for their second son in 2002, a path followed by Jon Bon Jovi.