Name Spellings, Initials and Sounds
Cool Names with a Strong O
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About this list
Baby names that begin or end with the letter O have long been particularly cool, especially (though there are a few feminine selections) for boys. The most popular girl name in the US, Olivia, has a strong O beginning, as does its rising masculine counterpart, Oliver. Both names are extremely popular throughout the Western world.
Along with Olivia and Oliver, other cool names with a strong O in the US Top 250 include Arlo, Diego, Enzo, Leo, Mateo, Milo, Olive, and Theo. Names with multiple Os may be especially cool — such as Apollo, Oona, Otto, and Rocco.
The options for cool names starting or ending with O range far beyond those offered here, of course, especially considering the entire world of Latinate baby names out there, but this group should give you a pretty good start.
The names
Olivia
Latin
"olive tree"
Olivia, a lovely Shakespearean name with an admirable balance of strength and femininity, is one of the top girls' names around the world. 2025 marked its 7th consecutive year in the #1 spot in the…
Oliver
Germanic, Latin
"elf army; ancestor's relic; olive tree"
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…
Mateo
Spanish
"gift of God"
Mateo is a Latinate name that like Mia and Luca, is becoming popular far beyond its native Spanish community. With its fresh feel and charm, it made a surprise entrance to the boys' Top 10 in 2023.…
Leo
Latin
"lion"
Leo is a strong-yet-friendly name that was common among the Romans, used for fourteen popes, and is now at its highest point ever in the US. Brave but sparky, Leo has ranked in the Top 20 in the US,…
Owen
Welsh
"young warrior; well-born"
Owen, a resonant Celtic name, has ranked among the Top 100 boys' names in the US for 20 years and is now at its highest point ever. Why do so many parents love Owen? It's a classic with a genuine…
Enzo
Italian variation of Henry, German
"estate ruler"
You may be surprised to know that Enzo is now a Top 100 boy name in the US and the UK, where it has been climbing straight uphill since the turn of this century. Enzo originated as the Italian…
Theo
Diminutive of Theodore
"gift of God"
See the popularity graph below for the name Theo? It's been heading straight uphill since 2010, when it hopped back onto the Top 1000 after a 60+ year absence. Now in the Top 100 in this form, Theo's…
Leonardo
Italian and Spanish variation of Leonard, German
"brave lion"
For centuries this name was associated primarily with the towering figure of Italian Renaissance painter-scientist-inventor Leonardo da Vinci, and was scarcely used outside the Latin culture. But…
Lorenzo
Italian; Spanish, variation of Laurence
"from Laurentium"
Latinizing Lawrence gives it a whole new lease on life. Like Leonardo, Lorenzo has been integrated into the American stockpot of names, partly via actor Lorenzo Lamas. Other associations are with…
Milo
Latin and Old German
"soldier or merciful"
Milo is most commonly considered to be Germanic name derived from the Latin word miles , meaning "soldier." However, there is evidence to suggest it also may have independently spawned from the…
Arlo
Irish or English
"between two hills"
Quirky cool Arlo is now well and truly back. Last year it broke into the US Top 200 boy names and consistently ranks among the most popular boy names on Nameberry. Along with its Irish and English…
Emilio
Spanish and Italian variation of Emil
"rival"
Dashing and suave, with a hint of poetry and gentleness, Emilio is an appealing and international choice. A solid favorite in Italy, it is also on the rise in the US, France, Austria, and the UK.…
Oakley
English
"oak wood or clearing"
Oakley, with its nature name roots and its Annie Oakley charm, is a hot name for both genders but more than twice as popular for girls. This name made it into the Top 1000 for the first time in 2013,…
Diego
Spanish variation of James
"supplanter"
The energetic Diego is rising rapidly along with a lot of other authentically Spanish baby names that work perfectly well with surnames of any origin. Possibly a derivative of Santiago, Diego is a…
Nico
Italian diminutive of Nicholas, Greek
"people of victory"
Nico is one of the great nickname names, full of charm, energy and effortless cool -- a neo Nick. Nico is commonly heard in Italy -- as a short form of Niccolo -- and also in France, Belgium,…
Antonio
Spanish and Italian variation of Anthony
"from Antium"
Antonio is a Shakespearean favorite -- the Bard used it in no less than five of his plays, and has long been a ubiquitous classic in Spanish-speaking countries, where the nickname Tonio is also…
Alejandro
Spanish variation of Alexander
"defending men"
Softer and smoother than Alexander, this classic Spanish name for boys has made a seamless transition to this culture. Adding to its current impact: the Lady Gaga song Alejandro .
Olive
English, from Latin, nature name
"olive tree"
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…
Oscar
English or Irish
"God spear, or deer-lover or champion warrior"
Oscar is one of the most stylish Old Man Names of our era. While it's softened slightly in popularity over the past 20 years, that may be considered a very good thing. In the nineties and the…
Omar
Arabic, Hebrew
"flourishing, thriving; eloquent"
A multicultural choice with an appealing open O sound, Omar blends stately strength with familiarity. Also transcribed as Umar, it is a popular choice among Muslim families and features in the name…