An order of succession is the sequence of those entitled to hold a high office such as head of state or an honour such as a title of nobility in the order in which they stand in line to it when it becomes vacated. This sequence may be regulated through descent or by statute.

An established order of succession is the normal way of passing on hereditary positions, and also provides immediate continuity after an unexpected vacancy in cases where office-holders are chosen by election: the office does not have to remain vacant until a successor is elected. In some cases the successor takes up the full role of the previous office-holder, as in the case of the presidency of many countries; in other non-hereditary cases there is not a full succession, but a caretaker chosen by succession criteria assumes some or all of the responsibilities, but not the formal office, of the position. For example, when the position of Catholic Pope becomes vacant, the College of Cardinals collectively carries out the essential functions of the papacy until a successor is elected.