The characters in the books are all anthropomorphic animals of some sort, almost all of whom are capable of speech (with a few exceptions like the horse in Redwall), which Jacques renders as various dialects of English. With a few rare exceptions, such as the monitor lizards from The Pearls of Lutra, other reptiles and the Jerbilrats of Loamhedge, the flora and fauna in the Redwall books are all native to Britain.
Despite the fact that Redwall is a fantasy series, it contains no elements of magic. Occasionally, elements of the supernatural or paranormal appear, mainly in two forms. First, the ghost of Martin the Warrior or another long-dead hero will often appear in hallucinations, dreams or visions to one of the woodland creatures (usually, but not always, an Abbey-dweller) and impart information. The information is always accurate (though often in the form of a riddle) and is of a nature such that it must have come from the ghost of Martin the Warrior and could not be the result of a creature "solving" a mystery in its sleep and dreaming about Martin the Warrior on its own. Also, some creatures in the books are called "seers" and claim to be able to see the future. While some of these "seers" turn out to be frauds, others such as the seers of Outcast of Redwall, Loamhedge, Taggerung and Lord Brocktree are quite real and play a key part in the turning of events in these books. Virtually all of the seers, both real and fraudulent, are vermin, who are generally considered more primitive and superstitious than woodlanders and other goodly creatures and are almost always the "bad guys." However, in the book Tribes of Redwall Mice, both Martin the Warrior and Abbess Germaine can foresee the future. Also present is the sword of Martin the Warrior, which is believed by many creatures (especially vermin, who in some instances try to steal it) to be magical. This sword was forged from the fragment of a shooting star (meteorite) at Salamandastron by Badger Lord Boar The Fighter in the book Mossflower.
Though the primary location is an abbey, and a church of St. Ninian's makes appearances, there has been no mention of a creator or godlike deity. In The Legend of Luke, a song is sung about how "St. Ninian's" is a misnomer from a sign that originally read "This ain't Ninian's!," after a mouse named Ninian refused to help his wife build a house; some of the lettering later wore off, leaving ironically the words "s ain't Ninian's," although the church is mentioned as having a lady chapel. However, there have been at least three mentions of the devil, Hell and other demons. After sending one of his minions to death, Cluny the Scourge roars "Tell the devil Cluny sent you!" On another occasion Constance the Badger makes a reference to "Hell's whiskers." According to the ferret Killconey, the snake Asmodeus is named for "the devil himself (the name itself, Asmodeus, is a reference to Asmodai)." There are also numerous references to "Hellsgate" throughout the series. While these references from Redwall, the first book, were made before the series had truly realized itself, Taggerung makes references to an underworld again when a devilish character called "Vulpuz" is mentioned by one seer as the ruler of Hellgates and the ancestor of foxes. In The Bellmaker, Mariel states, in the face of almost- certain death of her and her companions, that "the only way for them to go now is up". In several of the later novels, whenever a creature dies, characters make references to "The Dark Forest" or "Hellgates" as places where creatures go after death. The Dark Forest however, has not been explained further.
Books in the series often contain one or more "monsters," but these are not mythical creatures, rather being some type of ferocious predator. Monsters have included snakes, and adders (from Redwall, Doomwyte, and Triss), large carnivorous fish such as pikes, and sharks (from Marlfox, The Bellmaker, Triss, Lord Brocktree, and Mossflower), a plesiosaur-type creature (from High Rhulain), a wolverine (from Rakkety Tam), a scorpion (from Mariel of Redwall) and a giant sea serpent (from Salamandastron and High Rhulain though mentioned very very briefly in the latter), along with an eel (from Mossflower, Taggerung, The Long Patrol, and The Sable Quean), a giant lobster (Mariel of Redwall) and crabs (from Mossflower and Lord Brocktree).
A typical book in the Redwall series details a particular period in the history of Redwall Abbey. In all but a few cases, the book is about the inhabitants of Redwall and the surrounding Mossflower Woods. Usually, there are at least two different stories going on. For example, a typical book may relate the story of a small expedition by a group of woodlanders, as well as the story of a large group of Redwallers at home fending off a vermin horde. Because of the widely spaced storylines (chronologically speaking), very few creatures are mentioned in more than one or two novels, except in a passing historical sense. One notable exception is Martin the Warrior, who appears in all books, even if, most of the time, only in spirit form or no more than as a passing historical mention. Additionally, Martin's sword is present in all of the novels. Though he is not mentioned by name in Lord Brocktree, Martin is referred to in Brocktree's dream as "a young mouse bearing a beautiful sword." A second exception is the badger Cregga Rose-Eyes, who appears in three books: The Long Patrol, Marlfox, and Taggerung.
Other recurring elements and characters in the Redwall series include Badger Rulers and Badger Mothers, "Dibbuns" (the Redwall name for infant woodlanders), a Skipper of Otters, Foremoles, hares, helpful birds, one or more Log-a-logs (a shrew tribe leader), and mouth-wateringly detailed descriptions of (almost entirely vegetarian) food, which are called "vittles."