Freya has long been popular in the U.K. but has only taken off in the US in the last decade, along with the entire category of mythological names. Derived from the Old Norse name Freyja, meaning "Lady, noble woman", Freya is the name of the Norse goddess of love, beauty, and fertility.

Floral, elegant, and bold, Ophelia re-entered the US Top 1000 in 2015 after more than 50 years off the charts. It has risen more than 700 spots since then and shows no signs of slowing down. Now in the US Top 300, could Ophelia one day become the next Olivia or Amelia?

Josephine, with its large measure of class and character and a gently offbeat quality, has been on a gentle uphill climb in the US for over 30 years, now ranking in the Top 100. With an intriguing number of vivacious nicknames, from Jo to Josie to Fifi to Posy, Josephine is a Nameberry favorite.

Oliver is an international star, ranking near the top of the charts throughout the English-speaking world and in a host of European and Latin American countries, from Norway to Chile, Slovenia to Switzerland. Why? Because Oliver is energetic and good-natured, stylish but classic, with a meaning symbolizing peace and fruitfulness.

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.

Though some might find it a bit heavy-booted, Ivan is one of the few Russian boys' names to become fully accepted into the American naming pool.

More famously spelled Wallis as a feminine name: the woman for whom the King of England abdicated the throne.