There are two primary characters in Heaney's "Casualty." Neither of them is named. To an extent, the "casualty" himself seems to represent many similar men who had the misfortune to veer away from their "tribe" and were met by fatal violence in war-torn 1970s Ireland. Thus, there is a universal applicability to the poem. At the same time, the poet takes care to describe his "casualty" in loving and specific detail. He is not simply an archetype; we know that he "drank like a fish," didn't shrink from asking questions about worlds which were "incomprehensible" to him, and gestured for a fresh drink with a jerk of his "weathered thumb." As an older man, he had "tact" and was "observant" but lived on the "dole" (a British and Irish term for welfare or state benefits). Reluctant to obey the curfews placed upon the city or the warnings issued by the soldiers stationed there, the man lost his life at the hands of a parachute regiment, along with twelve others.

The other main character in the poem is the speaker himself. We can assume that, as in many of Heaney's poems, this character is largely autobiographical. Certainly he is a poet, and his "art" is of interest to the "casualty," even though it is not something that would be part of his world. The speaker seems to have known the "casualty" socially. He thinks of him now, wondering what he might ask if he were to return as a "revenant" and ask the speaker, an educated man, to make sense of the situation.

To a significant extent, the two characters in the poem are individuals affected by the same plight of a divided Ireland. They paint a picture in which others might recognize themselves. At the same time, they are specific and universal to their context and time.