Better strictly as nicknames

Finn is a name with enormous energy and charm, that of the greatest hero of Irish mythology, Finn MacCool (aka Fionn mac Cuumhaill), an intrepid warrior with mystical supernatural powers, noted as well for his wisdom and generosity.

Mia is an appealingly unfussy multicultural name that has enjoyed a meteoric rise up the charts and is now firmly among the ten top girl names. Mia has surpassed its mother name Maria as the Number 1 girls' name starting with M.

Mae, a sweet and springlike old-fashioned name, hadn't been on the national charts in forty years, but finally made it back in 2010. Mae is derived from May, the month name that was chosen for its connection to Maia, the Roman goddess of growth and motherhood.

Jack may have fallen from its Number 1 place in England, but in the US it's as popular as it was at its height in the 1920s and 1930s. A durable, cheery, everyman form of John, Jack ranks as one of the most popular boy names starting with J.

Kai is an internationally flexible name with many possible origins and meanings, growing in popularity in the US and a diverse range of European countries.

Although Sylvia seems to be having somewhat of a revival among trendsetting baby namers, we'd still opt for the even gentler and more unusual Sylvie. Despite being dated in its native France (where it was popular during the 1950s and 60s), in English-speaking regions it still feels fresh and international without being unfamiliar and has a cosmopolitan, international air. It debuted on the US Top 1000 in 2016.

Elsie is a sweet vintage nickname-name turned modern star. After a 30-year hiatus, Elsie started climbing the US popularity list 20 years ago and is still headed for the top.

Maisie, a charming name long popular as a nickname for Margaret or Mary, entered the Top 1000 as itself ten years ago and continues to rise. Game of Thrones star Maisie Williams helped propel the name back into the limelight, along with the that of her character, Arya.

River shares the tranquil feeling of all the water names, and seems to have pretty much escaped its past strong association with River Phoenix and his unfortunate fate. Actor Joaquin Phoenix named his son with actress Rooney Mara after his brother River.

Mila is a popular name that took a 125 year nap, ranking in the Top 1000 in 1881 and then not ranking again until 2006, after actress Mila Kunis appeared on That 70s Show.

Beau suggests someone devilishly handsome, with a large measure of southern charm—a nice image to bestow on your boy. Often solely a nickname in the past, it's now standing firmly on its own. Beau has been on the Social Security list non-stop since 1969.

Ellie first took off in the UK—yes, in this nickname form—and this warm and friendly name has also become hugely popular here. In 2011, Ellie entered the US Top 100 girl names for the first time and has remained near the top of the charts ever since.

Ella is a sweet, simple name that owes much of its current popularity to the popularity of other names, from Emma to Bella to Emily to Ellie.

Nina is as multiethnic as you can get: Nina is a common nickname name in Spain and Russia, a Babylonian goddess of the oceans, and an Incan goddess of fire. Here and now, it's a stylish possibility that's been underused. "Weird Al" Yankovic chose this decidedly nonweird name for his daughter.

Harry is the medieval English form of Henry, which derived from the Germanic name Heimrich, meaning "estate ruler." Harry was the nickname of all eight King Henrys; it is also a diminutive of Harold and Harrison.

Friendly mega-popular short form of Katherine that has definitively replaced Kathy, Katie is often given on its own. Going forward, though, Katie is more stylishly clipped itself to the grownup Kate.

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.

Jackson is one of those names that's much more popular than you think, coming in near the top of our annual Playground Analysis, which ranks names by grouping all their spellings together. Last year, more than 13,000 baby boys were named Jackson -- along Jaxon, Jaxson, Jaxxon, Jaxen, Jaxyn, Jaxsen, and Jaxsyn -- which counted together makes it the Number 5 boys' name.

Kate, in the headlines via Catherine Middleton aka the Princess of Wales, has been as pervasive as Kathy was in the 1950s and 1960s, both as a nickname for Katherine and Kaitlyn and as a strong, classic stand-alone name.

A name that has a bit of a shouldn't-I-be-a-middle-name sound, though still in use as a first for both genders. Lee might be a good choice if you want something that sounds at once traditional yet modern, unisex but not newly-minted.