Lucas is a Top 10 boys' name with a slightly-less-popular almost-identical twin brother, Luke. Like Elijah and Elias, Lucas and Luke come from the same root and have the same meaning and so feel even more popular than they are.

The related Lucas and Luke are both hugely popular boy names in the US and internationally, and now Luca has joined them on boys' popularity lists around the world.

Luke is a cool-yet-strong Biblical name with a relaxed cowboy feel, which has been on the rise since the advent of Luke Skywalker.

Very much a boy's name in Italy, it's beginning to be seen as a unisex possibility here: actress Jennie Garth used it for her daughter, as did influencers Alyssa and Dallin Johnson, When spelled Lucca as in the Italian city, it can also be considered one of the place names along with Venezia, Roma, and Milana that make great Italian names for girls.

Luc is the sleeker Gallic cousin of Luke, and if you want to know the difference between their pronunciations, just watch Kevin Kline's hilarious description in the film French Kiss. Peter Gabriel and Sean Patrick Thomas picked this version for their sons.

The Polish form of Lucas has long been popular there, but is on the decline now.

The most popular short form of Lucas in the Netherlands, the other being Loek.

An example of the traditional French/Catholic style of double names starting with Jean: in this case, two Gospel writers. Star Trek, Captain Jean-Luc Picard is from 24th-century France, where the French language is almost extinct, but parents apparently still give their children classic French names.

One of many Luca variations making its way up the charts.

Form of Lucas found in the Czech Republic and Slovakia.

One of the many rising variations of Luca.