Ancient Egyptian mortuary cult is one of the most fascinating subjects for whoever approaches ancient Egypt and a recurrent topic in previous and current research on ancient Egyptian beliefs and practices. One key aspect for understanding the mortuary cult is, doubtlessly, its agents, the 'priestly officiants' that once performed the rites with the ultimate expectation to ensure an escape from death for the deceased. Despite their significant role, there are not many works particularly devoted to the mortuary 'priesthood' in ancient Egypt, and even less for a period as remote as the Old Kingdom. In view of this, Priestly officiants in the Old Kingdom mortuary cult aims at filling the gap in the Egyptological literature by incorporating into the discussion comprehensive analyses of eight of the most prominent priestly titles of the period. Thus, the main goal is to consolidate our insight of the role of those who guarded, developed, and sustained the most professional duties involved in the respect and care for the dead and their memory. The most noteworthy figures in the mortuary cult from both private and royal domains are the subject of a thorough examination covering the nature and development of each title, its functions and domains of practice, the most critical sources for their study and its historical evolution with a fresh approach that incorporates the newest theories and positions in the study of the Old Kingdom mortuary officialdom.