Durarara also comes to mind. Fate Zero, although it's not Loads of Characters does a great job balancing perspectives. Some shounen are surprisingly good at it too. I'd say Naruto, Fairy Tail and One Piece are great.
Visual aids really help people remember characters. I mean I still have problems remembering every Jack and Jill from GoT, but the visual format really helps in remembering them.
Naming can also be pretty helpful. You want to be able to make memoreable names that are not too common for people to get mixed up with. Tokyo Ghoul is brilliant and has loads of characters, but ever since I started the second 'season' of the manga I'm seeing old names that I completely forgot about.
In any case, unless a reader is completely lost and feels nothing for any of the characters, having more characters is actually a plus to your story. All the more better if you show antagonists and protagonists alike. It's always impressive to have characters love an antagonist who develops well over time, or the seemingly useless character meet a big hero and/or end up being really important to the plot in some way or the other.
It's my personal opinion, but absolutely avoid those 20-paragraph charts that detail everything from the character's favourite food to how they would react in a certain situation or not. You can develop that in retrospect, but more often than not you see them do something other than what you detailed in such a sheet.