This is an opinion question, and therefore should not be answered.
I however disagree with the above answer, even though it is only my opinion. It all depends on what your greatest quality is. For example, ThunderClan is for the brave. WindClan is for the fast. ShadowClan is for those who love the darkness. And RiverClan is for the swimmers. Or, in the cats cases, you are born their and are raised that way. But in my case, I am in of course RiverClan.
You can't if your not in a clan your a loner! Sorry
shadowclan
Thunderclan
The clan leader is the first in charge in warrior cats. He/She makes orders to the clan and the clan is supposed to obey. They are called chieftains or patriarchs.
The size varies but ThunderClan has the biggest clan.
To fight, protect and serve their clan even at the cost of their life. Stay loyal to your clan.
The clan where warrior cats go when they die is called StarClan. It is a group of the spirits of deceased warriors, leaders, and medicine cats who watch over and guide the living cats of the forest.
I mean Thunder clan like from the warrior series but you should have 15-20 cats in that clan
FireClanWildClanLeafClanCloudclanMoonClanStormWindClanStormClanBlueClanSilverClanDarkClanArticClanDustClanSnowClanMidnightClanForestClanWoodClanNightclanIceclanStreamclanLotusclanBirdclanWhisperclanMoonclanMidnightclanDuskclanDawnclanAshclanBlackclanSnakeclanBirdclanTreeclanFlowerclanBerryclan
In may 2010
A ceremony consists of an apprentice being accepted as a warrior, or a kit being old enough to become an apprentice. Apprentice to warrior - The apprentice is brought up before the Clan to receive their warrior name and rank from the Clan leader. They must say "I do" to questions asking for their loyalty and courage. The Clan leader then gives the apprentice their new name, and the new warrior will spend the night on camp watch. Kit to apprentice - The kit is brought up before the Clan to receive their apprentice name and rank from the Clan leader. They must say "I do" to questions asking for their loyalty and courage. The Clan leader then gives the kit their new name, and the new kit will move into the apprentice's den.
A human can't but a rogue or a loner could join a Clan.