Tenebrae (—Latin for "darkness") is a religious service of Western Christianity held during the three days preceding Easter Day, and characterized by gradual extinguishing of candles, and by a "strepitus" or "loud noise" taking place in total darkness near the end of the service.

Tenebrae was originally a celebration of matins and lauds of the last three days of Holy Week (Maundy Thursday, Good Friday, and Holy Saturday) in the evening of the previous day (Holy Wednesday, Maundy Thursday and Good Friday) to the accompaniment of special ceremonies that included the display of lighted candles on a special triangular candelabra.

Modern celebrations called Tenebrae may be of quite different content and structure, based for example on the Seven Last Words or readings of the Passion of Jesus. They may be held on only one day of Holy Week, especially Spy Wednesday (Holy Wednesday). They may be held during the daylight hours and the number of candles, if used, may vary.

Tenebrae liturgical celebrations of this kind now exist in the Catholic Church's Latin liturgical rites, Lutheranism, Anglicanism, Methodism, Reformed churches and Western Rite Orthodoxy.