Olivia, a lovely Shakespearean name with an admirable balance of strength and femininity, is the Number 1 name for baby girls in the US and one of the top girls' names around the world.

Ottilie is trending in the UK, where the pronounced T helps the name sound pretty and delicate, rather like Amelie and Elodie. Ottilie is less popular in the US, where many Americans pronounce it as a near-homonym for "oddly".

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?

Odette is the good swan in Tchaikovsky's ballet Swan Lake, a role for which Natalie Portman won an Oscar ---and it would make a particularly sophisticated yet upbeat choice. In fact, it charted in the US charts in 2025 for the first time since 1905!

Though greatly overshadowed by the trendy Olivia, Olive has a quiet, subtle appeal of its own -- and is now enjoying a remarkable comeback. Olive is one of only four girl names starting with O on the US Top 1000. Cool couple Isla Fisher and Sacha Baron Cohen chose it for their daughter, reviving the name to stylishness, and now Drew Barrymore has a little Olive too, as has country singer Jake Owen.

Orla is an Irish name closely associated with the high king Brian Boru, as it was the name of his sister, daughter and niece. It was very popular in the Middle Ages – the fourth most popular name in twelfth century Ireland – and has become popular again in Ireland, Scotland, England and Wales today. In Irish, the name is commonly spelled Orlaith or Orlagh.

Opal is on the verge of a repolishing, following other jewel names like Ruby and Pearl. A Top 100 name during the first two decades of the twentieth century, the opalescent Opal has a good chance of coming back as another O-initial option.

Octavia began as the Latin, then Victorian name for an eighth child. While there aren't many eighth children anymore, this ancient Roman name has real possibilities as a substitute for the overused Olivia; recommended for its combination of classical and musical overtones. It was chosen for his daughter by Kevin Sorbo.

Odessa, (transcribed as Odesa in Ukrainian) is a Ukrainian port city and was given its name by Catherine the Great, who was inspired by Homer's Odyssey. It would make an original and intriguing choice.

Oona is a name made famous by Eugene O'Neill's daughter, who became Charlie Chaplin's wife. One of the original Oona's granddaughters was named after her, and is now an actress famous in her own right for playing Talisa of Volantis in HBO's "Game of Thrones." The double-o beginning gives their name a lot of oomph.

Oriana is a dashing medieval name, with a meaning similar to Aurora. At this point, though, Oriana is much more unusual than Aurora and makes a unique choice if you're searching for names that mean new beginnings or dawn.

Onyx is a fresh and trending gemstone name for boys, currently in the US Top 500, having climbed the charts rapidly since 2018. Now, an increasing number of girls are receiving the name, with a recent count revealing nearly 200 baby girls were called Onyx in 2023.

Odette's evil Swan Lake twin -- gives the name a sinuous, sensuous appeal. It was a popular choice in France in the 20th century and made the Top 40 back in 1952, however, it has since fallen out of favor.

Curiously appealing, in a hoop-skirted, wasp-waisted way, Ottoline has recently entered the realm of modern possibility, especially since Sienna Miller chose it as the middle name of her daughter Marlowe.

A particularly beautiful member of the Oriana and Orane clan,Oriane is the first name of a major character in Proust's In Search Of Lost Time, the Duchesse de Guermantes. Also borne by climber Oriane Bertone, the name may derive from the Latin aurum meaning "gold" or from oriens meaning "rising, sunrise". It was give to just 8 girls in a recent year in the US, but was a popular choice in France in the 2000s.

With its relation to Mount Olympus, home of the Greek gods, and to the Olympic games, this name has an athletic, goddess-like aura, making it the perfect Olivia substitute.

This Slavic form of the Norse name Helga is a classic in many Slavic countries, including Russia and Poland, where it currently ranks within the Top 100 girl names. It has historically ranked among the most popular names in countries including Ukraine, Latvia, Spain, France, Serbia, Greece, the US, and many more. Olga is a common name even in Scandinavian countries, such as Sweden and Norway, despite Helga being a more traditional choice. Olha is the uniquely Ukrainian variation.

In early, pre-Norman Ireland, this name was borne by both a sister and a niece of high king Brian Boru. Now, the English form Orla is more commonly used.

Olwen is a Welsh favorite, the name of a legendary princess in what is believed to have been the earliest Arthurian romance, and in fact one of the first recorded examples of Welsh prose.

French variation of Ophelia that might make that lovely-and-haunted name feel more viable, yet there will be inevitable pronunciation issues.