Boy names ending in the letter O have been fashionable for a couple of decades now, with many of the most popular choices zooming to the top of the list.

The best boy names ending in O include selections from those top names as well as unique O-ending names. The Top O-ending boy name in the US right now is the Spanish Mateo. Along with Mateo, other boy names ending in O in the US Top 500 include Leo, Santiago, Milo, and Theo.
Unique boy names ending in O that make our best list include Anselmo, Benno, Caio, and Laszlo.
Of course, O is the usual ending for boys' names in Italy, Spain, and other Latinate countries. O-ending boys' names popular internationally include choices from those lands as well as boys' names with other origins that carry the O ending.
We've included a few fashionable names here that don't technically end in O but in the O sound.
If you want to explore beyond our Best List, see our master list of nearly 1800 <a href="https://nameberry.com/baby-names/901/boy-names-ending-in-o">boy names ending in o</a>.

Boy Names Ending in O

This name of a California desert town, used by Deborah Falconer and Robert Downey, Jr. for their son, makes a much livelier and more individual – not to mention more masculine – improvisation on the themes of India and Indiana.

 The similar sounding color name Indigo is unisex – it was used by Lou Diamond Phillips for his daughter, as well as the group The Indigo Girls, but its o-ending makes it boy-friendly too.

Indio

Claudio, a most appealing Italian name, is featured in not one, but two Shakespearean plays, ,Measure for Measure and Much Ado About Nothing. While "lame" is the most widely acknowledged meaning, some etymologists theorize that the name may relate to the word for enclosure or clause, an alternate meaning that may appeal to a child with a form of this otherwise-attractive name.

Claudio

Natalino is the jaunty Italian male nickname for the gender-neutral Natale. And it has that fashionable o ending. Natalino might work as a nickname for Nathaniel too.

Natalino

Artemio gives energy to this august Greek mythological name.

Artemio

Cesario is a masculine name with Italian and Spanish origins, derived from the Latin name 'Caesar,' which means 'long-haired' or 'head of hair.' Historically, the name carries prestigious connotations due to its association with the Roman Julius Caesar and the subsequent imperial title. Cesario has remained relatively uncommon in English-speaking countries, maintaining its distinctive character as a heritage name in Italian and Hispanic communities. The name appears in literature, most notably in Shakespeare's 'Twelfth Night,' where Viola disguises herself as a character named Cesario. With its melodic quality and rich historical connections, Cesario offers a distinctive option for parents seeking a name with classical roots and a romantic Mediterranean flair.

Cesario

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.
 The Roman statesman known as Cato the Elder was born Marcus Portius, the Cato added in tribute to his natural sagacity, practical wisdom and political expertise.
 Cato appears in Shakespeare's Julius Caesar and, to go from the sublime to the ridiculous, in the Pink Panther movies--and Kato was The Green Hornet's valet. Cato is also a 21st century Hunger Games name, which could do more to spur its popularity than all its past history.

Cato

Cassio is a notable Shakespearean name that's a member of the ever-more-popular Cassius family of names.  Cassio was Othello's young, good-looking, and flirtatious lieutenant.

Cassio

Names ending with O are popular, but this one is almost unheard-of. Faro has the advantages of being easy to spell and pronounce (unless it's confused with Pharaoh), and a bright meaning. Ultimately it comes from Pharos, the island where the great Lighthouse of Alexandria was built, and there's a district and city in Portugal called Faro. Be aware: it's also the name of a gambling card game, highly popular in the nineteenth century before poker took over.

Faro

Calisto is a masculine name derived from Greek mythology, where Callisto was a nymph who was transformed into the constellation Ursa Major. The masculine form shifts the mythological association while maintaining the celestial connection. The name comes from Greek 'kallistos' meaning 'most beautiful.' While the feminine form Callista is more common in English-speaking countries, Calisto offers a distinctive alternative for boys. The name carries an artistic, sophisticated quality with its classical roots and melodic sound. Popular in some Latin cultures, Calisto provides a unique option that balances exotic appeal with historical depth. Its connection to the stars gives it an aspirational, expansive quality that many parents find appealing.

Calisto

Joyful-sounding name that makes a really original option.

Caio

Best Boy Names Ending in O

Best boy names ending in the letter O, including Arlo, Thiago, Milo, and Theo with origins, meanings, and popularity (Page 8)