ThunderClan is a mainly peaceful Clan, and respectful of the other Clans as well. In battle, ThunderClan is fierce, courageous, and loyal. They are known to often take loners and kittypets into their Clan to either swell their ranks or because the cat is in need of help or shelter, although this did not happen much until Firestar became leader of ThunderClan. For this, they are at times looked down upon by other Clans and thought of as weak. The Clan's main prey are mice, voles, squirrels, and the occasional rabbit, as well as birds such as starlings, magpies, wood pigeons, blackbirds, and thrushes. They have excellent stalking techniques, creeping across the forest floor. They have the sense to keep upwind of their prey in the thick bushes. ThunderClan cats are noted to be especially strong. They are the only Clan to bunch their hindquarters before leaping to catch their prey.

ThunderClan was founded by Thunderstar. He is a large, fiery ginger-and-white tom with amber eyes, and big white paws. The first medicine cat was Cloud Spots.