Celebrated in song—the rock 'n' roll classic "Louie, Louie"—this is a gregarious, friendly spelling of Louis not often used as a full first name. It reentered the US Top 1000 in 2015. It's a highly popular choice in England and Wales.

If Lulu and Lula and Lou all work for girls, why not Louie? We're predicting a rise for baby girls in the wake of all the Lou names trending.