Start with Into the Wild. It is the first novel of the first Warriors arc, and for a name attached to more than eighty books it is the only entry point that does not drop you into the middle of somebody else's grandchildren.
The thing to sort out before anything else is the name. Erin Hunter is not a person. It is a shared pen name worked by a rotating team: the editor Victoria Holmes plotted the early books, and Kate Cary, Cherith Baldry, Tui Sutherland, Gillian Philip and others have written under it since. That is why one apparent author seems to have produced several enormous animal series at the same time — Warriors, Seekers, Survivors and Bravelands — and why searching the name returns a wall of covers with no front door. Warriors is the series people mean, and it is built in arcs of six novels each.
Arc one: The Prophecies Begin
Into the Wild, Fire and Ice, Forest of Secrets, Rising Storm, A Dangerous Path, The Darkest Hour. Read them strictly in that order. A house cat called Rusty leaves his garden, joins ThunderClan and is renamed Fireheart, and the first two books teach the fixed rules every later book assumes without re-explaining: the four Clans, the warrior code, and the naming system that turns a kit into an apprentice into a warrior. Forest of Secrets is where the series stops being a school story with cats — the parentage secrets that drive the next twenty books are planted there.
Where you are allowed to stop
The Darkest Hour is a genuine ending. It resolves the prophecy stated in the first chapter of Into the Wild, and a reader who stops there has read a complete six-book story with nothing missing. Everything after it is optional, which is worth knowing before you commit to eighty volumes.
The one Super Edition to read next
Firestar's Quest is the first of the longer standalone Super Editions, and it belongs here rather than later — it works as an epilogue to arc one and answers a question The Darkest Hour deliberately leaves open. The other Super Editions (Bluestar's Prophecy, Crookedstar's Promise, Yellowfang's Secret, Tallstar's Revenge) are prequels and can be read at any point afterwards.
Arc two: The New Prophecy
Midnight, Moonrise, Dawn, Starlight, Twilight, then Sunset. The viewpoint moves to the next generation, and Dawn destroys the forest the first six books were set in, forcing the migration that fixes the geography of every book after it. Two warnings. The sixth volume, Sunset, is not in our catalogue, so find it separately rather than stopping the arc one book short. And the fifth, Twilight, is a Warriors novel with no connection to the vampire series of the same name — the two get confused constantly in secondhand listings.
Arcs three and four
The Sight opens Power of Three and The Fourth Apprentice opens Omen of the Stars. These two arcs share one story and The Fourth Apprentice spoils the central reveal of the one before it, so read Power of Three in full first. Neither is a place to start a newcomer; both assume the whole of arcs one and two.
The other Erin Hunter series
The Quest Begins opens Seekers, about three bear cubs, with noticeably more real natural history than Warriors. The Empty City opens Survivors, about dogs in a city emptied by an earthquake, and is the closest in structure to Warriors — packs instead of Clans. Bravelands, set on the African savannah, begins with Broken Pride. All are separate continuities and each starts clean.
For the adult handing these over
Stated as plain fact rather than as warning: these are books about wild animals and the violence is not stylised. Cats are wounded in territorial battles, named characters including kits are killed, the deaths are permanent, and a major antagonist commits murder inside his own Clan. The Darkest Hour is the most violent book of the first arc.
One buying note. Searching for the first book as "Warriors: Into the Wild" often returns a three-book bind-up rather than the single novel. Search by author, check the page count, and expect around 320 pages. The full Erin Hunter hub collects what else on the site sits near this.
Follow the full ordered path here: Warriors books in order: where to start with Erin Hunter.