The Lost Boys are characters from J. M. Barrie's play Peter Pan, or The Boy Who Wouldn't Grow Up and subsequent adaptations and extensions to the story. They are boys "who fall out of their prams when the nurse is looking the other way and if they are not claimed in seven days, they are sent far away to the Neverland" where Peter Pan is their captain. There are no "lost girls" because, as Peter explains, girls are far too clever to fall out of their prams.
In the Peter and the Starcatchers series, an earlier group of Lost Boys include boys whom Peter knew from St. Norbert's orphanage, and who return to England with the heroine's family at the end of the prequels. This description does not concord with the canon backstory for the Lost Boys, who are not orphaned, but lost as babies.
In Peter and the Secret of Rundoon, some other boys from St. Norbert's, who used to be slaves for King Zarboff, end up going to Neverland with Peter. Their names are:
By the end of the novel, Prentiss, James, Tubby Ted, and Thomas decide to go back to London with Leonard Aster because they realize they would become men some day and cannot keep up with Peter forever. They leave for the real world and all grow up. Peter and Tinker Bell take in the new, more familiar Lost Boys. However, Peter is reunited with James, who has grown up, in the fourth novel, Peter and the Sword of Mercy.
In Peter Pan in Scarlet, Tootles becomes a girl because he only has daughters to borrow clothes from in order to become a child again and go back to Neverland. He finds his father, who is a judge, too.
Nibs is the only Lost Boy not to return to Neverland because he can't bear the thought of leaving his children. Because of this he also is the only one who never meets his real parents, stays an orphan and has no chance to learn anything of his earlier life.
Slightly plays the clarinet and saves the day a couple of times with his music. Slightly grows up to marry a noblewoman and becomes a lord, though he has become a widower at the age of thirty and is the only one of the Lost Boys not to father any children. He gets tricked by the new enemy when he returns to Neverland and grows up, much to Peter's anger. Thanks to his love for music he finds his real mother and after returning to London he is the only Lost Boy who doesn't return to his adult age, but stays eighteen and stays with his mother.