Stephen Burt enumerates the many ways poets can show up in their work:
It seems to me that poetry in general lets you create a voice that is you-but-not-you, you-but-like-you, you-as-someone-else, for the writer and also for the reader: that character can speak about you, for you, to you, in ways that you couldn’t pull off speaking “as yourself.”
Sometimes the persona, the you-who-speaks-the-poem, has no name and not much extension other than what’s brought about by the author’s style (the “I” in a lot of poems by Emily Dickinson), and sometimes the persona has a great deal of extension, a prior life as a historical or fictional character (Robert Browning’s Andrea del Sarto), and sometimes the persona’s somewhere in between (Philip Sidney’s Astrophel). Even a poem that looks autobiographical constructs a character anyway — it’s just that the character shares obvious attributes, such as location, approximate age, and marital status, with the “bundle of accident and incoherence who sits down to breakfast,” as Yeats put it, the real-life poet who wrote the poem.
The Dish 