Samhain marks the Day of the Dead and the coming of winter.  It is Gaelic for “summer’s end.” Along with Imbolc, Beltane and Lughnasadh it makes up the four Gaelic seasonal festivals. It was observed in Ireland, Scotland and the Isle of Man. Kindred festivals were held at the same time of year in other Celtic lands; for example the Brythonic Calan Gaeaf (Wales), Kalan Gwav (Cornwall) and Kalan Goañv (Brittany). Wiccans celebrate a variation of Samhain as one of the yearly Sabbats of the Wheel of the Year. It is deemed by most Wiccans to be the most important of the four ‘greater Sabbats.’ It is generally held on October 31 in the Northern Hemisphere, starting at sundown. Neopagans in the southern hemisphere often celebrate Samhain at the other end of the year (~30 April–1 May).  As there are many kinds of Neopaganism, their Samhain celebrations can be very different despite the shared name. Some try to emulate the historic festival as much as possible. Other Neopagans base their celebrations on many unrelated sources, the Gaelic culture being only one of the sources.  Some combine African, Asian and/or  Native American culture in their rituals.  While Samhain is celebrated as a cultural festival by some (though it has mostly been replaced by Halloween), since the 20th century, it has been celebrated as a religious festival by many Neo-pagans, including most Wiccans.

For Neo-Pagans and most Wiccans, it is a time for honouring departed spirits and reflecting on changes in their lives.  It often involves paying respect to ancestors, family members, elders of the faith, friends, pets and other loved ones who have died. In some rituals the spirits of the dead are invited to attend the festivities. It is seen as a festival of darkness, which is balanced at the opposite point of the wheel by the spring festival of Beltane, which Wiccans celebrate as a festival of light and fertility.

To most modern Pagans, while death is still the central theme of the festival this does not mean it is a morbid event. For Pagans, death is not a thing to be feared. Old age is valued for its wisdom and dying is accepted as a part of life as necessary and welcome as birth. While Pagans, like people of other faiths, always honour and show respect for their dead, this is particularly marked at Samhain. Loved ones who have recently died are remembered and their spirits often invited to join the living in the celebratory feast.

Halloween or Hallowe’en (a contraction of “All Hallows’ Evening”), also known as All Hallows’ Eve, observed annually in a number of countries on October 31, was according to many scholars,  originally influenced by western European harvest festivals and festivals of the dead with possible pagan roots, particularly the Celtic Samhain.