Beginning at line 32 of the first canto of the Inferno section of his poem The Divine Comedy, Dante introduces three beasts. These are encountered by the speaker as he moves through an obviously allegorical dark forest. The beasts are, respectively, a leopard, a lion, and a female wolf.
The symbolic significance of the beasts has been interpreted in different ways. According to James Finn Cotter, in his helpful annotated translation of the poem (see link below),
The allegorical meaning of the three beasts is not clear. One tradition maintains that the leopard is probably symbolic of fraud; the lion (l .45) of violence; and the she-wolf (l. 49) of incontinence. Since these make up the three chief divisions of hell, the poet first encounters them in reverse order.
Professor Guy Raffa provides an extremely helpful discussion of the symbolism on his web site Dante’s World (see link below):
The uncertain symbolism of the three beasts--a leopard (or some other lithe, spotted animal), a lion, and a she-wolf--contributes to the shadowy atmosphere of the opening scene. Armed with information from later episodes, commentators often view the creatures as symbols, respectively, of the three major divisions of Dante's hell: concupiscence (immoderate desires), violence, and fraud (though some equate the leopard with fraud and the she-wolf with concupiscence). Others associate them with envy, pride, and avarice. Perhaps they carry some political meaning as well (a she-wolf nursed the legendary founders of Rome--Romulus and Remus--and thus came to stand as a symbol of the city). Whatever his conception, Dante likely drew inspiration for the beasts from this biblical passage prophesying the destruction of those who refuse to repent for their iniquities: "Wherefore a lion out of the wood hath slain them, a wolf in the evening hath spoiled them, a leopard watcheth for their cities: every one that shall go out thence shall be taken, because their transgressions are multiplied, their rebellions strengthened" (Jeremiah 5:6).
Always, when reading a poem as old and as complicated as Dante’s, it is important to do some research to determine the various ways in which particular symbols may have been interpreted, both in Dante’s time and also later. Fortunately, the internet now makes such searching extremely easy. If, for instance, you search for “Beasts in Canto I of Dante’s Inferno,” you will find an extraordinary amount of information. You should perform this search not only on Google but also in Google Books. You should particularly look for annotations in different editions of Dante. Many of these can be found by searching on amazon.com. (Search for “Dante’s Inferno” or “Dante’s Divine Comedy.”) Almost every edition of the poem will provide explanations of symbolism, but those explanations may differ from one edition to another. It’s important, then, to see if any broad consensus exists among the different editions.
The more important the work of literature, the more likely it is to have generated many different interpretations. (A walk through the Shakespeare section of any decent library will confirm this claim.) This is why it's important not to assume that any particular interpretation of any work of literature is necessarily the "correct" interpretation.