Silverstream had her kitting in a riverbank cave near ThunderClan territory in the book Forest of Secrets in the Warriors series.
Yes, she dies in The Forest of Secrets, which is the first book of the first series, bearing Graystripe's kits.
Yes, Foxleap dies in the Warriors series. He dies in the battle against the Dark Forest.
In "Warriors: Omen of the Stars - The Fourth Apprentice," Russetfur, a ThunderClan warrior, dies during the battle with the Dark Forest warriors.
He dies when frieheart is trying to make it to yellowfang. Yellowfang is the medicine cat. But medicine cats cannot have kits. So she gave up brokentail. Brokentail began to murder other clan cats, so yellowfang fed him death berries.
He will die with all of Thunderclan by his side, even some Starclan warriors like Bluestar and Yellowfang. He dies from his wounds in the battle with the Dark Forest.
Blackstar, the leader of ShadowClan in the Warriors series, dies in the battle against the Dark Forest in "The Last Hope." He was killed by a Dark Forest warrior named Hawkfrost.
Well, there has to be some romance and tragedy to be exciting.
Honeypaw dies from Greencough, a fatal sickness that affects cats, in the Warriors series by Erin Hunter.
Yes, Hollyleaf dies in "The Last Hope" when she sacrifices herself to save Ivypool from Hawkfrost during the battle against the Dark Forest.
In the book Dawn, (the New Prophecy), she stayed behind in the old forest with Frostfur, Loudbelly and Shadepelt when the clans left on the Great Journey.it was later comfirmed that she and the other cats that stayed behind died of starvation a few moons after the clan had left. Although it does not say what book.
Bluestar dies in "Forest of Secrets" after sacrificing her life to save Fireheart (Firestar) from a pack of dogs. She drowns in the river while protecting ThunderClan's camp.