Penelope is an unlikely 21st century baby name success story. Off the Top 1000 for 25 years, Penelope jumped back on in 2001 and has been heading uphill ever since, propelled by the trend for mythological names, Spanish actress Penelope Cruz, and some high-profile celebrity babies.

Alexander has been in a Top 25 boys' name in the US for 30 years now. But namers are still attracted to its imposing historic pedigree.

Florence is back, returning to the US Top 1000 girl names in 2017 after a nearly 40 year absence. Other English-speaking countries have been quicker to welcome Florence back into fashion.

Adeline has a lovely, old-fashioned "Sweet Adeline" charm, but has become so popular in the US under so many spellings and variations — with Adalynn and Adalyn also popular — that considered together it is far more popular than it first seems. Adorable nickname Addie is also pervasive.

Caroline is a perennial classic, one of the elite group of girls' names that's ALWAYS ranked among the Top 1000 and that's been in the Top 100 since 1994. Elegant yet strong, Caroline calls to mind the Kennedy Camelot years and Princess Caroline of Monaco.

Frances, a soft and gentle classic last popular a hundred years ago, is trending again. The cool nickname Frankie is one reason for the revival of Frances, adding lightness and sass to a serious name. Frances is the feminine form of Francis, the English variation of the Latin name Franciscus. Franciscus, meaning "Frenchman," was taken from the Germanic tribe the Franks, which got its name from the francisca, the axe they used in battle. Until the seventeenth century, the spellings Frances and Francis were used interchangeably for both sexes.

Levi, lighter and more energetic than most biblical names, with its up vowel ending, combines Old Testament gravitas with the casual flair associated with Levi Strauss jeans.

Margaret is derived from the French Marguerite, which in turn came from Margarita, the Latin form of the Greek Margarites. Margarites was based on the Old Persian word margārīta, meaning "pearl."

Nathaniel was derived from the Hebrew name Netan’el, meaning "gift of God," composed of the elements natan, meaning "to give," and ’el, in reference to God. The name is featured several times in the Old and New Testaments, typically spelled Nathanael. In the New Testament, Nathanael is also known by his other name, Bartholomew.

Clementine is a Nameberry favorite that broke back into the US Top 1000 in 2014 after more than half a century off the list.

Cecilia is a lovely classic name deservedly enjoying a new turn in the sun. Always among the Top 500 girls' names in the US, Cecilia is now at its highest point ever.

Abigail has been in for so long -- the name has ranked in the US Top 100 since the late 1980s -- it's amazing that it isn't more out by now. But Abigail's biblical and historic roots make it a fashionable classic rather than a passing fad.

Adelaide is now heading straight uphill on the coattails of such newly popular sisters as Ava, Ada, and Audrey, and in the company of Adeline and Amelia. It was chosen by actress Katherine Heigl for the name of her second daughter.

Molly is one of the original nickname names, ALWAYS ranking among the US Top 500 girl names since statistics began, in 1880. Molly peaked in 1991 only to rise just as high again in 2011, and though softening retains a good measure of popularity and charm.

John reigned as the most popular of all boys' Christian names for 400 years, from the time the first Crusaders carried it back to Britain until the 1950s. Then American baby namers finally seemed to tire of this straight-arrow, almost anonymous John Doe of names, replacing it with fancier forms like Jonathan and the imported Sean and Ian.

Elizabeth is one of the most popular girls' names of all time, the female equivalent of James or William. Yet Elizabeth has so much going for it—rich history, broad appeal, and timeless style—that no matter how many little girls are named Lizzie, Eliza, and Beth, you can still make Elizabeth your own.

A short but strong biblical name with multicultural appeal, Asa is enjoying new visibility thanks to hot young actor Asa Butterfield of Hugo fame.

Lottie is a nostalgic great-grandma name that conjures up lockets and lace, and — like Nellie, Josie, Hattie, Tillie, and Milly — has considerable vintage charm.

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.

Robert was the Number 1 boys' name in the US in both 1925 and 1950, and in fact was in the Top 25 for more than a century, giving it true classic status. Strong if not quite stylish, Robert remains in the Top 100 for baby boys as a family favorite.