Spellmaster
I probably see most of the cats wrong because I don't know what so many of them are supposed to look like… Unless they're described a lot or I have to check the allegiances a lot, I tend to just forget the specifics. there's too many of them…
I think I always imagined Firestar as mostly solid orange, but I can easily see him with tabby stripes too. Yellowfang is still kind of a dull yellow-gray to me. Dustpelt has always been gray-brown because dust being brown does not make sense to me. Longtail… I think I remember mostly as light brown, but I never quite understood his markings so I probably went back and forth with black and silver and everything.
I've always thought of Hawkfrost as a very pale brown tabby… I guess because of the 'frost' in his name? I feel like he should be lighter than he is.