Among the hardest cases in the ethics of killing are those in which one innocent person poses a lethal threat to another. I argue in favour of the intuition that lethal self-defence is permissible in these cases, despite the difficulties that some philosophers (e.g., Otsuka and McMahan) have raised about it. Philosophers writing in this area—including those sympathetic to the intuition (e.g. Thomson and Kamm)—have downplayed or ignored an essential and authoritative role for intuition per se (as against discursive general principles): one based in moral sensibility and imagination rather than discursive argument or conceptual analysis. I am concerned to call attention to and rehabilitate this role for intuition.