The aim of the paper is to examine Seneca’s self-portrait as depicted in his Letters to Lucilius. The first part deals with the place this collection of letters occupies in the context of ancient epistolary literature. It shows how it contributed to the introspective character of ancient philosophical prose. Introspection as a method of self-knowledge and self-creation is analyzed in the second part. The resulting vision of the identity of the author of Letters is neither unified, nor consistent: Seneca is presented as a “man of many faces” in his life as well as in literature.