A variation of Jenson, which is actually more popular than the original in the United States. This spelling also holds the distinction of being the most common surname in Denmark.

This quintessentially common last name makes a distinctive if first, given to more than 230 babies in the US in the most recent year counted. It has doubled in use over the last decade.

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.

Jason, the Number 3 name for the entire decade of the 1970s -- thus the title of our original baby-naming book, Beyond Jennifer & Jason -- is more likely to be dad's name now than baby's, but it's still a widely used name.

Justin has been widely popular since the 1980s, when parents were seeking a fresher 'J' boys’ name to replace Jason, Jeremy and Jonathan. It's been dipping in popularity a bit in recent years but it reached as high as Number 9 in 1990. At this point it's Justin that is suffering from overexposure.

Juniper is a nature name that we really like. While it's trendiest for girls -- about 2500 baby girls were named Juniper in 2022 versus 34 baby boys -- the most notable Juniper in history was the saint Brother Juniper, a follower of Saint Francis renowned for his generosity. Blessed Junipero Serra, who founded the first of the California Missions, took his name from the earlier Saint Juniper.

Reminiscent of 70’s favorite Jason, and sharing sounds with the perpetually popular James, Jayden is one of the more enduring members of the -ayden trend.

With its cool -X ending, Jax is an update on the classic nickname Jack, likely inspired by the rise of Jackson. It garnered attention in the US thanks to the game, Mortal Kombat II back in the '90s, and was pushed up the charts when it was used in the show Sons of Anarchy, in which Jackson "Jax" Teller is the central character.

Jethro, though the biblical father-in-law of Moses, has suffered for a long time from a Beverly Hillbilly image, but some really adventurous parents might consider updating and urbanizing it and transitioning it into the hip o-ending category.

Immortal through its association with the ancient Caesar (it was his clan name), Julius may still lag behind Julian, but is definitely starting to make a comeback, and in fact feels more cutting edge, in line with the current trend for Latin -us endings.

Jaunty, to say the least, Jonty might be an option if Johnny feels too old school. It has been noticed most often on the playing fields, as in U.K. rugby player Jonty Parkin (born Jonathan) and South African cricketer Jonty Rhodes (Jonathon).

Actor Joaquin Phoenix (brother of River, Rain, Liberty and Summer) highlighted this one, then Kelly Ripa began talking about younger son Joaquin on her daily TV show, and presto—it's now one of the hottest and most appealing multicultural baby boy names.

Julien is the handsome French form of Julian, which derives from Julius, a Roman family name. Its origin is shrouded in history, but possible roots include Latin iuvenis, meaning "youthfu"; Greek ioulos, meaning "downy-bearded"; or Jovis, a form of Jupiter, which means "sky father".

Jedidiah, an Old Testament name with a touch of Gunsmoke-era western panache, is right in line to be revived along with the other biblical -iah names.

Judah is the strong, resonant Old Testament name of the son of Jacob who was the ancestor of one of the tribes of Israel, and from whom the word Jew is derived. Some of the names' popularity might be attributable to the similarly named Jude Law.

A biblical place name with trumpeting verve and strength.

One of the most enduring French names, this form of John has been borne by philosophers (Rousseau and Sartre), artists (Millet, Arp) and fashion designers (Gaultier) alike. Often used in a double name with the likes of Pierre, Paul, and Luc, it is a classic in its native country,

Joe is still the ultimate good-guy name, not at all diminished by its longevity or popularity or its everyman rep as Regular Joe, Cowboy Joe, G.I. Joe, Joe Exotic, Joe Blow, Joe Millionaire, Average Joe — and now President Joe (Biden).

Justice, one of the rare virtue names for boys, entered the popularity ranks in 1992, and remained in the charts until the 2020s. While it has fallen out of favor in more recent years, it remains a fresh but solid feeling option.

Jupiter's partner Juno has entered the mainstream, so it's possible that her divine mate could follow. But not necessarily for boys — Jupiter is currently mostly female in the US, thanks to its similarity to Juniper. Stars including Ed Sheeran and Ashley Tisdale recently welcomed daughters named Jupiter, which could shift the balance even more towards the girls.