Allhallowtide, Hallowtide, Allsaintstide, or the Hallowmas season is the Western Christian season encompassing the triduum of All Saints' Eve (Halloween), All Saints' Day and All Souls' Day, as well as the International Day of Prayer for the Persecuted Church and Remembrance Sunday in some traditions. The period begins on 31 October annually. Allhallowtide is a "time to remember the dead, including martyrs, saints, and all faithful departed Christians." The present date of Hallowmas and thus also of its vigil (Hallowe'en) was established for Rome perhaps by Pope Gregory III (731–741) and was made of obligation throughout the Frankish Empire by Louis the Pious in 835. Elsewhere, other dates were observed even later, with the date in Ireland being 20 April. In the early 11th century, the modern date of All Souls' Day was popularized, after Abbot Odilo established it as a day for the monks of Cluny and associated monasteries to pray for the dead.

Halloween or Hallowe'en is a celebration observed in many countries on 31 October, the eve of the Western Christian feast of All Hallows' Day. It is at the beginning of the observance of Allhallowtide, the time in the liturgical year dedicated to remembering the dead, including saints (hallows), martyrs, and all the faithful departed. In popular culture, the day has become a celebration of horror, being associated with the macabre and supernatural.