Halloween started as an ancient festival. What was it called

Samhain

The All Saints Day celebration was also called All-hallows or All-hallowmas (from Middle English Alholowmesse meaning All Saints' Day) and the night before it, the traditional night of Samhain in the Celtic religion, began to be called All-Hallows Eve and, eventually, Halloween.

The All Saints Day celebration was also called All-hallows or All-hallowmas (from Middle English Alholowmesse meaning All Saints' Day) and the night before it, the traditional night of Samhain in the Celtic religion, began to be called All-Hallows Eve and, eventually, Halloween.