In Goidelic mythology, Lasair ("flame") was the eldest of three sisters (along with Inghean Bhuidhe and Latiaran, daughters of Douglas and Scathach) associated with the harvest. She represented the summer and was the goddess of growing crops. She had long black hair and wore a silver crown, jewelry and armbands. Her home was called Red Castle. A god named Flann brought her the Rose of Sweetness (a flower that never dies), the Comb of Magnificence and the Girdle of Truth.

After Christianization, she was turned into a saint. Her feast day was May 1.

Alternative: Lassar, Fhína ("flaming wine"), Lasairíona ("flaming wine"), Crobh Dearg ("red claws")