There are many houses and other groups in the novels. The most well-known ones being House Atreides, House Harkonnen, the Bene Gesserit, and the Fremen. But Frank Herbert’s created many other groups in his fictional universe, some of which gradually evolved, and some which just died out.
Which is the one you are most fascinated with? And why do you find them so interesting?
Probably the Honoured Matres because of what they are and their rivalry with the Bene Gesserit but also the insight into Herbert’s mind lol.