There is only one character in this poem: the speaker. This is not uncommon in lyric poetry. However, this poem is in many ways very much focused on character. The speaker is very clearly delineated within the poem: he is someone who has experienced an enormous amount of suffering, and yet who retains an impressive strength of spirit. He is self-determined and self-aware. He has little faith in anything except for himself, but his faith in his own strength is immense.

While it is generally a fallacy to equate a poem's speaker with its author, Henley himself described "Invictus" as an autobiographical representation of his struggles with pain, illness, and stigmatization. As such, the speaker can be interpreted as both a universal voice for strength in the face of adversity, and as Henley himself, speaking for those traditionally alienated by Victorian society.