Hermione Marshall, a British teenager who works in a flower shop, was named after the heroine of the Harry Potter books and films. A 6-year-old in Ohio shares his name with Ollivander, the magical wandmaker from the series. Venerable wizard Albus Dumbledore has a namesake—a second-grader from Las Vegas who loves a good outer-space joke.

Parents have long named their kids after favorite characters across pop culture. “Game of Thrones” fans called their girls Daenerys (before the Mother of Dragons ruthlessly burned a city to the ground). Elsa became popular after “Frozen” came out. Now, as young readers who grew up with Harry Potter become parents themselves, they have given their children names straight out of the roll-call at Hogwarts.