If you’re under 30, Monkey D. Luffy, the zany captain of the Straw Hat Pirates, in the Japanese manga and TV show “One Piece,” and the ninja leader Naruto and his adolescent son, Boruto, from a different series, probably rank among your favorite animated characters. If you’re over 30, they’re the stars of the biggest franchises you’ve never heard of.

Their worldwide popularity is staggering. Since Eiichiro Oda began “One Piece” in 1999, more than 430 million books have been sold and 848 episodes of the television series have been broadcast. The two “Naruto” TV show ran for 720 episodes.

Fewer people know that the English voices of these rambunctious males are supplied by women: Maile Flanagan, 53, plays Naruto; Amanda Miller, 31, is Boruto; and Colleen Clinkenbeard, 38, is Luffy. In the United States, actresses often voice young boys — Nancy Cartwright has long played Bart Simpson, and the late June Foray did scores of kids in Jay Ward cartoons — but rarely do they speak for athletic teenagers or adult men. (In Japan, all three characters are also voiced by women.)

Ms. Clinkenbeard, who will appear at New York Comic Con x Anime Expo, which begins Thursday, said: “I’m always surprised when fans are surprised because it’s been going on for so long. Someone will come up to my table at a convention to get my autograph as one character, see a poster that says that I’m also Luffy and be shocked.”