A separate article is titled Columba (constellation).

See Columba (genus) for the genus of doves and pigeons.

Saint Columba (7 December 521 - 9 June 597), the Latinized version of the Gaelic name Saint Columcille meaning "Dove of the church", was an Irish missionary monk who helped re-introduce Christianity to Scotland and the north of England.

He was born to Fedhlimidh and Eithne of the Ui Neill clan in Gartan, near Lough Gartan, Donegal. On his father's side he was great-great-grandson of Niall of the Nine Hostages, an Irish king of the fourth century. He became a monk and soon rose in the church hierarchy to the rank of priest. Tradition asserts that, sometime around 560, he became involved in a dispute with Saint Finnian over a psalter. Columba copied the manuscript at the Scriptorium under Saint Finnian, intending to keep the copy. Saint Finnian disputed his right to keep the copy. The dispute eventually led to the pitched Battle of Cul Dremhe in 561, during which many men were killed. (Columba's copy of the psalter has been traditionally associated with the Cathach of St. Columba.) As penance for these deaths, Columba suggested that he work as a missionary in Scotland to help convert as many people as had been killed in the battle. He also promised to move from Ireland and never again to see his native island.

He travelled to Scotland, where it is reputed he first landed at the southern tip of the Kintyre peninsula, near Southend. However, being still in sight of his native land he moved further north up the west coast of Scotland. In 563 he founded a monastery on the island of Iona off the west coast of Scotland which became the centre of his evangelising mission to Scotland. There are many stories of miracles which he performed during his mission to convert the Picts.

Columba is also the source of the first known reference to the Loch Ness Monster. According to the story, in 565 he came across a group of Picts who were burying a man killed by the monster, and brought the man back to life. In another version, he is said to have saved the man while the man was being attacked, driving away the monster with the sign of the cross.

St Columba's feast day is June 9 and with Saint Patrick, March 17, and St. Brigid, February 1, is one of the three patron saints of Ireland.

Columba is not to be confused with his disciple, Saint Columbanus.