The title '''''protosyngellos''''' (in Greek, προτοσυνκελλος; also spelled '''''protosynkellos''''' or '''''protosyncellus''''') is an honorific given by the [[bishop]] to a high-ranking [[clergy|cleric]] in a [[diocese]], usually a [[priest]]. The protosyngellos is often the most senior cleric in the diocese after the bishop. It is sometimes given simply to whomever has the most [[presbeia|seniority]], but it may also be an office, often translated into English as '''''chancellor'''''.
The term ''protosyngellos'' literally means "first cellmate." A ''syngellos'' is simply the cellmate of a monastic, while the cellmate of the bishop (who may often be a monastic) is styled the ''protos'' among the ''syngelloi''. In the early use of this title, it referred to a monastic who lived with the bishop and served him.