Cats of course! lol Its about feral cats that live in Clans. They live by a "warrior code" and train to be warriors.
There are 4 series of 6 books and then 6 super edition books. The first series of 6 books follows the point of view of a house cat that joins the Clans and ends up saving the forest. The second series follows the point of view of many cats and they have a prophecy with cats from the other Clans.. not going to go into much details other than that. The third series brings in magic. Its about three cats born with the power of the stars. The fourth series is about the three saving the whole forest and StarClan (which is the dead ancestors).
The super editions (except two) tell the life story of cats throughout the books.
There is also another series that is currently being released that tells the story of how the Clans started.
They are very good books.
I got my husband into them also.
They are considered a "kids intermediate" series for some reason, but I know many people our age and some older who enjoy them.
My username is a cat from the third and fourth series. He's one of my favorite characters.
They are by Erin Hunter, which is actually three different women under the alias that Harper Collins gave them. They also have another series about bears written under the name Erin Hunter, but I haven't read this series... However, the series called "Survivors" (about dogs) is not by the same people but Harper Collins used the name "Erin Hunter" for these books to sell them... I haven't read them either but I've heard bad things about them and by the looks of them, they seem like they are written on a easy reading level.