Riley—an upbeat, friendly surname name—is red hot for girls and still going strong for boys. If you haven't been spending much time around babies recently, you may be surprised to learn that Riley is the most popular girls' name starting with R and also the Number 1 Irish name for girls in the US.

Quinn is one of the most popular Irish unisex surnames out there, a strong and attractive choice on the rise for girls but still popular for boys. A recent year saw it used for nearly 2690 girls along with 615 boys in the US, meaning its split 80:20 across the sexes.

Morgan has long been a traditional Welsh male name, a variant of the Old Welsh name Morcant, from the Welsh elements mor, meaning "sea" and cant, "circle." The female Morgan is unrelated to the male version—it is a name from Arthurian legend created for Morgan le Fay, King Arthur's half-sister and famed sorceress. Her name comes from Morgen, an Old Welsh name meaning "sea-born," and is related to the Irish name Muirgen.

A favorite in England and Wales, Darcy is a unisex option with delicacy, grace, and strength. Associated with classic literary and courtesy thanks to Jane Austen's hero, Mr. Darcy, and Bridget Jones's Mark Darcy, its image was partly transformed by English ballerina Darcey Bussell, who helped popularize it for girls.

You might think of Harper as the hottest name of the last decade, jumping from obscurity to the Top 10, where it remained until last year.

Sasha, largely male in Russia--and also spelled Sascha and Sacha--is an energetic name that has really taken off for girls here, chosen by Jerry Seinfeld (using the alternate Sascha spelling) and other celebs. The Barack Obamas use it as the nickname for their younger daughter, whose proper name is Natasha. But in line with a trend toward softer-sounding boys' names like Asher and Joshua and thanks to Borat star Sacha Baron Cohen, Sasha also still has life as a boys' name too--it's popular in France for boys and girls almost equally.

Avery is a hugely popular name in the US, especially for girls. But while nearly four times as many girls as boys are named Avery today Avery's popularity is starting to soften for girls while it continues to strengthen for boys.

Rory is a buoyant, spirited name for a redhead with Celtic roots. The name Rory is getting more popular overall, but for the past few years has been trending decidedly toward the boys' side -- however, it's been rising to new heights for girls in recent years.

Alexis, a one-time exclusively-boys’ name, was more popular than its sister Alexandra for quite a while, but in recent years Alexandra has overtaken it once again. Alexis was a Top 20 girls’ name from 1994-2010 but has experienced a decline in popularity in recent years, though now it's one of the top unisex names.

Billie is a tomboy nickname name, part of the growing trend for using boyish nicknames for girls and now destined for stardom along with its most famous contemporary bearer, music sensation Billie Eilish.

The e-addition takes the name from slightly hippie-ish nature name to the place name of a picturesque island off the coast of Scotland, and for baby namers it's by far the more popular spelling.

Almost like a fusion between vintage Audrey, bubbly Ruby, and unisex Avery, Aubrey has been a popular choice for girls since the mid 2000’s.

The sassy, steel magnolia appeal of Oscar-winning Reese (born Laura Jeanne—Reese is her mother's maiden name) Witherspoon has single-handedly propelled this formerly boys’ name into girls' popularity.

Skylar is a name with a hint of both edginess and whimsy and it makes for a nature-inspired choice that is neither too wordy nor too floral. Popular since the 90s, Skylar has remained in the US Top 100 for over a decade and is the most popular spelling of the name for girls.

Originally used for children baptized in holy water from the river Jordan, it became one of the leading androgynous names of the nineties. As the balance tips toward the boys' side, it's slipping on the girls' popularity chart. Alternate spelling Jordyn is now more popular for girls.

Taylor is one of the prime unisex surnames used for girls and has also been a soap opera favorite. Taylor was in the Top 10 for the last several years of the twentieth century, so that now it tends to feel a little nineties – though Taylor Swift is keeping it in the spotlight and Tay is a charming nickname. Garth Brooks and Bryan Cranston have daughters named Taylor; Taylor Schilling portrays lead Piper Chapman in Orange is the New Black.

Boys' favorite retains more of its poetic, windswept quality when used for a girl, as Robin Wright and Sean Penn did. Alyssa Milano gave her daughter Elizabella Dylan as a middle name.

Ashley was a sensation in the 1980s and 1990s; it hit Number 1 in 1991. Ashley is still pretty but more and more parents are turning to newer names like Ashlyn and Aubrey, and spellings such as Ashleigh and Ashlea. If you hear the name Ashley in a playground today, it's more likely to be the mom than the little girl.

This name found in both Celtic and Scandinavian mythology has gone from all-boy to almost all-girl, retaining a strong, unisex quality. However, it has dropped following its three-decade heyday from the 1960s to the 1990s.

Cameron was once a rising star for boys only, but Cameron Diaz almost single-handedly transported it into the unisex camp back in the 80s.Though there are still eight times as many boy babies named Cameron as girls, it is currently in the US Top 600, where it is joined by Camryn and Kamyn.