The speaker of the poem
The speaker of the poem could be considered as a character of the poem, as the voice of the speaker is directly involved with the poem, providing arguments for religious conviction. This speaker's directness correlates to the poet's religious convictions and beliefs.
The tiger
The tiger is present in the poem as a divine creature and a creature confined to its skin. At one point, the tiger is described as a watchful divinity, and at another as a creature confined to passions of its blood.
The Man
The Man only appears in the final line separated from the rest of the natural world. The man with his mind ajar is not a direct part of the praise of the creation. The message conveyed with this separation is that the man refuses to let his mind completely be opened up to see the proofs in the creation, as the speaker of the poem intended, of the religious convictions.