Five New Species, many new characters
At the end of Crystal Pyramid the Valtorian tells the Alpha Team members that they are only two of twelve species who are the children of the Gods. In Star Children the explorers travel to an area of space 200 light years from League space and find five of the missing ten species engaged in an interstellar war. They are the Finuls, the Castarians, the Landorians, the Axions and the Aldarians. This means there are characters from five new species in addition to the three species (the Humans, the Ventrons, and the Beltarians,) that were in Crystal Pyramid. Then of course there is the Galaxy Keeper. All this means that Star Children has a large cast.
If you have not yet read the book, I suggest you meet the characters in the story as it progresses rather than viewing their biographies ahead of time, perhaps referring back here as the various species and characters are introduced to get additional information. Learning too much about the characters in advance may disclose too much of the story prematurely.
Use the buttons on the right to learn more about each species and the members of each species that play a significant role in Star Children.