It has been widely acknowledged in the areas of human memory and cognition that behaviour and emotion are essentially grounded by autobiographic knowledge. In this paper we propose an overall framework of human autobiographic memory for modelling believable virtual characters in narrative story-telling systems and role-playing computer games. We first lay out the background research of autobiographic memory in Psychology, Cognitive Science and Artificial Intelligence. Our autobiographic agent framework is then detailed with features supporting other cognitive processes which have been extensively modelled in the design of believable virtual characters (e.g. goal structure, emotion, attention, memory schema and reactive behaviour-based control at a lower level). Finally we list directions for future research at the end of the paper.