Saint Brigid of Kildare or Saint Brigid of Ireland (Irish: Naomh Bríd; Classical Gaelic: Brighid; Latin: Brigida; c. 451 – 525) is the patroness saint (or 'mother saint') of Ireland, and one of its three national saints along with Patrick and Columba. According to medieval Irish hagiographies, she was an abbess who founded the important abbey of Kildare (Cill Dara), as well as several other convents of nuns. There are few historical facts about her, and her hagiographies are mainly anecdotes and miracle tales, some of which are rooted in pagan folklore. They say Brigid was the daughter of a chieftain and a slave woman, and was raised in a druid's household before becoming a consecrated virgin. She is patroness of many things, including poetry, learning, healing, protection, blacksmithing, livestock and dairy production. In her honour, a perpetual fire was kept burning at Kildare for centuries.

Some historians suggest that Brigid is a Christianization of the Celtic goddess, Bríd. St Brigid's feast day is 1 February, and traditionally it involves weaving Brigid's crosses and many other folk customs. It was originally a pre-Christian festival called Imbolc, marking the beginning of spring. From 2023 it is a public holiday in the Republic of Ireland, the first named after a woman. This feast day is shared by Dar Lugdach, who tradition says was her student, close companion, and successor. The occasion is marked on the first Monday on or after 1st February.