The below list contains major spoilers for KILLBOY including major character deaths.
- Graphic mechanized and infantry combat; dismemberment, immolation, crushing
- Mass civilian casualties, described institutionally (casualty figures as market data)
- Death of children, including a first-person account by the soldier responsible
- Maiming; a character's arm and eyes destroyed on-page; prosthetics and surgical replacement
- Strangulation
- Execution by sidearm at close range
- Radiation injury; catastrophic nerve destruction; burned bodies
- Interrogation and detention
- Killing a mentor and friend
- The killing of a Native person at the hands of a half-white military soldier
- Killing a lover, by hand, at length, while conscious of doing it
- The death of multiple LGBT or LGBT-coded characters, often violently
- Invocation of the 9/11 attacks in mechanically central ways
- A parent killed by the protagonist's own side, in an act the protagonist supports
- Cruelty to a parent — deliberate, sustained, in service of self-preservation
- Bereaved family confronting the person responsible
- Gender assigned by military induction; a founding text defining "woman" as the non-soldier
- A protagonist forcibly and administratively misclassified/misgendered for her entire adult life; documents overwritten
- Self-directed allegorical transphobia and misogyny; the protagonist's own contempt for women, including herself
- Misogynist slurs and abuse
- Neural surveillance conducted through a person's body without her knowledge or consent
- Human experimentation; volunteers selected for the intensity of their attachments and burned alive
- Military indoctrination from early childhood
- Colonial occupation depicted via close analogue to the real US occupation of Hawaiʻi, including the seizure of ʻIolani Palace and the deliberate use of kindness toward children as a military recruiting instrument
- Racism, institutional and internalized; a colonized character who believes her people deserve their subjection
- Theocratic indoctrination; real scripture deployed as a military and fascist apparatus; an afterlife used as a recruiting promise
- Genocide, referenced and depicted
- Explicit sexual content (two scenes)
- One occurs between soldiers, one of whom is unknowingly instrumented as a surveillance device — the encounter is observed by the state through a participant who does not know it — it is also between a soldier and their superior officer
- One occurs with a nonhuman intelligence bonded to the protagonist's nervous system
- Tobacco use
- Suicide, in the specific sense of a fatal act undertaken deliberately, competently, and treated by the narrative as correct
- Dissociation; derealization; time distortion under fire