The 'chameleon poet' is a phrase immediately associated with Keats. Although he only used it once in a letter written early in his poetic career, the phrase has since gained currency in literary criticism and it now invokes a familiar set of assumptions about Keats and his works. My thesis offers a recontextualized understanding of the idea of the chameleon poet by showing how the phrase, rather than being a whimsical and idiosyncratic idea of Keats's own coinage, was in common currency during the nineteenth century, and how the seemingly unlikely analogy between a poet and a chameleon has several antecedents in earlier works. Not only has the chameleon been compared to poets, playwrights and actors, but the creature has been used in a figurative sense to describe a form of self endowed with . the ability to change. By tracing Itne literary heritage of the chameleon, I show how the model of self Keats embraces for the poet has more negative and troubling associations than Keats' s letter acknowledges. While a chameleon-like model of self offers positive attributes of responsiveness and changeability, more commonly the creature is referred to in a pejorative sense to register anxieties about the instability of identity, lack of integrity, capriciousness and duplicity. Having traced the literary context of the chameleon poet, I outline how Keats' s particular use of the phrase has been interpreted in literary criticism. I identify a tendency in scholarly responses to criticise the chameleon poet for its implicit amorality or apathy, or to explain away the idea on the basis that Keats in his poetry does not exemplify the model he set out for himself. However, as I aim to make 'clear in my discussion of Keats's poetry, by exploring ideas about transformation and disguise, sympathetic responsiveness, hypocrisy and the stability of selfhood, Keats's works reveal him engaging in a self-reflective manner with implications directly relevant to a chameleon-like model of .poetic self. By first identifying how Keats differs from the usually negative' interpretation of chameleon changefulness, I show that while Keats embraces the idea of a chameleon-like poet in his letter, his poetry reveals a more circumspective approach in which he registers the consequences that such a model entails.