The speaker in a poem or novel is called -

Persona:
The speaker in a poem or novel. The speaker is necessarily not the writer of the poem or novel.
For example -
The persona of Tennyson's 'Ulysses' is Ulysses, the Greek hero, not Tennyson.

Protagonist:
One who takes the leading part in a drama; hence, one who takes lead in some great scene, enterprise, conflict, or the like.
Antagonist:
One who contends with another, especially in combat; an adversary; an opponent.
Soliloquy:
An act of speaking one's thoughts aloud when by oneself or regardless of any hearers, especially by a character in a play.

Source: An ABC of English Literature - Dr M Mofizar Rahman