Necrostatin-5 (Nec-5) is a novel potent small-molecule inhibitor of necroptosis structurally distinct from previously described Necrostatin-1 (Nec-1), and therefore, represents a new direction for the inhibition of this cellular caspase-independent necrotic cell death mechanism. Here, we describe a series of structural modifications of Nec-5 and the structure-activity relationship (SAR) of Nec-5 series in inhibiting necroptosis.