There is increasing agreement that the current categorical system of personality disorders (PDs) in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 2000) should be replaced by a trait dimensional scheme in DSM-V. In particular, the consensus appears to be converging on a hierarchical Big Four model. The broad factors that form the apex of this hierarchy are essentially maladaptive variants of the Big Five traits of normal personality, minus Openness. We argue that this Big Four model is incomplete, however, in that it fails to model characteristics related to the "odd or eccentric" Cluster A PDs adequately. We report the results of three studies that examine these odd, eccentric characteristics in relation to basic dimensions of normal and abnormal personality. The results of these studies establish the existence of an Oddity factor that is (a) broader than the Cluster A traits and (b) distinct from Openness and the other Big Five dimensions. Consequently, its addition yields an alternative five-factor model of personality pathology (considering only abnormal traits) and an expanded, integrated Big Six taxonomy that subsumes both normal and abnormal personality characteristics.