This working paper summarizes what is currently known about cybercrime offenders and groups. The paper briefly outlines definition and scope of cybercrime, the theoretical and empirical challenges in addressing what is known about cyber offenders, and the likely role of organized crime groups (OCG). The paper gives examples of known cases that illustrate individual and group behaviour, profiles typical offenders, including online child exploitation offenders, and describes methods and techniques commonly used to identify crimeware and help trace offenders.