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1770+ Boy Names Ending in O

Pamela Redmond
By Pamela Redmond
Updated Sun Sep 29 2024
1770+ Boy Names Ending in O

Boy names ending in O offer many intriguing options, from such top names as Theo to unique O-ending names from Kylo to Zino.

Mateo is the most popular boy name ending with O right now, though there are nearly 100 O-ending boy names among the US Top 1000. Along with Mateo, other boy names in the US Top 1000 include Leo, Santiago, Diego, Romeo, and Antonio.

And there are hundreds more unique names for boys that end with the letter O worthy of your consideration. These range from the biblical Jethro to the ancient Greek Cosmo to the cool, modern Rio and Po.

Here are all Nameberry’s boy names that end with the letter O, ordered by their current popularity on Nameberry.

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  1. Milo

    • Origin:

      Latin and Old German

    • Meaning:

      "soldier or merciful"

    • Description:

      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 Slavic root milu, meaning "merciful." Milo predates brother name Miles, a variation that evolved when the name immigrated to the British Isles in the Middle Ages. Mylo is an alternate spelling.
  2. Arlo

    • Origin:

      Irish or English

    • Meaning:

      "between two hills"

    • Description:

      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.
  3. Hugo

    • Origin:

      Latinized form of Hugh

    • Meaning:

      "mind, intellect"

    • Description:

      Hugo, the Latin form of Hugh, has more heft and energy than the original -- and of course we love names that end (or begin, for that matter) with an o. This one is especially appealing because it's backed up by lots of solid history and European style.
  4. Leo

    • Origin:

      Latin

    • Meaning:

      "lion"

    • Description:

      Leo is a strong-yet-friendly name that was common among the Romans, used for thirteen popes, and is now at its highest point ever in the US thanks in part to Leonardo "Leo" DiCaprio.
  5. Otto

    • Origin:

      German

    • Meaning:

      "wealthy"

    • Description:

      Otto is cool again. Long a quintessential Old Man Name, Otto has been promoted to trending darling of adventurous baby namers.
  6. Elio

    • Origin:

      Italian, Spanish

    • Meaning:

      "sun"

    • Description:

      Elio is a sunny and spirited Italian and Spanish name that makes a great crossover prospect, which could catch on as Enzo has. Elio is also currently popular in France, ranking in the Top 250.
  7. Theo

    • Origin:

      Diminutive of Theodore

    • Meaning:

      "gift of God"

    • Description:

      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.
  8. Nico

    • Origin:

      Italian diminutive of Nicholas, Greek

    • Meaning:

      "people of victory"

    • Description:

      Nico is one of the great nickname names, full of charm, energy and effortless cool -- a neo Nick.
  9. Mateo

    • Origin:

      Spanish

    • Meaning:

      "gift of God"

    • Description:

      Mateo vaulted into the boys' Top 10 in 2023, ranking all the way up at Number 6. It is a Latinate names that, like Mia and Luca, is becoming popular far beyond its native Spanish community.
  10. Enzo

    • Origin:

      Italian variation of Henry, German

    • Meaning:

      "estate ruler"

    • Description:

      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.
  11. Apollo

    • Origin:

      Greek mythology name

    • Meaning:

      "destroyer"

    • Description:

      With mythological names rising, the handsome son of Zeus and god of medicine, music, and poetry among many other things might offer an interesting, if high-pressure, option.
  12. Ivo

    • Origin:

      German

    • Meaning:

      "yew wood, archer"

    • Description:

      Ivo is an unusual, catchy name with the energetic impact of all names ending in 'o'. Hardly heard in the U.S., it is used a bit more frequently in England, as is the related Ivor, a favorite of such novelists as Evelyn Waugh and P.G. Wodehouse. Ivo is currently most popular in the Netherlands.
  13. Cosmo

    • Origin:

      Italian, English, Greek

    • Meaning:

      "order, beauty, universe"

    • Description:

      With a touch of celestial power, a hint of clunky charm, and the totally cool -o ending, Cosmo may well be finally shaking itself free of both the Seinfeld association (which made it a punchline of a joke) and the cartoon fairy association from The Fairly OddParents. In fact, it is in the Top 1000 in the UK and a favorite on Nameberry.
  14. Cato

    • Origin:

      Latin

    • Meaning:

      "all-knowing"

    • Description:

      Cato conjures up images of ancient Roman statesmen and southern antebellum retainers; it could have revival potential, with its 'O' ending and the current interest in the names of Greek and Roman antiquity.
  15. Lorenzo

    • Origin:

      Italian; Spanish, variation of Laurence

    • Meaning:

      "from Laurentium"

    • Description:

      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 Lorenzo de' Medici, the Florentine Renaissance merchant prince and art patron, Renaissance artists Ghiberti and Lotto, and the upstanding young man who married Shylock's daughter Jessica in Shakespeare's The Merchant of Venice.
  16. Matteo

    • Origin:

      Italian

    • Meaning:

      "gift of God"

    • Description:

      This attractively energetic Italian version of the classic Matthew is primed to move further and further into mainstream American nomenclature. Mateo is technically the Spanish version, but many parents in the US use the two spellings interchangeably.
  17. Santiago

    • Origin:

      Place-name or Latin

    • Meaning:

      "Saint James"

    • Description:

      Santiago is a spirited Spanish name with great crossover potential. It's a place-name (a city in Chile), a surname, and the name of the patron saint of Spain.
  18. Rocco

    • Origin:

      Italian from German

    • Meaning:

      "rest"

    • Description:

      Madonna did much to polish up the image of this old-neighborhood Italian choice when she picked it for her son with British director Guy Ritchie, and several years later it was also used by Rose Byrne and Bobby Canavale for their son. It now feels much more mainstream than many celebrity baby names, sharing the quirky appeal of some other so-far-out-they're-in baby names as Bruno and Hugo.
  19. Leonardo

    • Origin:

      Italian and Spanish variation of Leonard, German

    • Meaning:

      "brave lion"

    • Description:

      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.
  20. Viggo

    • Origin:

      Scandinavian

    • Meaning:

      "war"

    • Description:

      Though to most Americans Viggo is a one-person name attached to intense actor Mortensen, it is actually an old Norse name dating back to the Vikings, and is currently the 32nd most popular appellation in Sweden. Viggo Mortensen is a Jr., sharing his name with his Danish father.