I hate reading books that have so many characters that I forget which is which, so I try not to do it myself. One of the recent ones I'm working on though has a lot. There are two main characters, seven more very involved characters, and so far thee minor chararacters, all in the space of 20 pages.I've done my best to introduce them in stages, first just four of them, and making sure they are fully covered, then added annother two and covered them. Then I switched to a different group, and added those ones one at a time. They are all very different people, and have (what I think) names that are easily remembered. But how many is too many? I'm thinking of books like the Harry potter series, which have dozens of characters, and trying to make my characters distinguishable like that, but still I don't want to end up with 30 boring characters that don't know whats going on.