Donadea (Irish: Domhnach Dheá) is a civil parish in the barony of Ikeathy and Oughterany in the north of County Kildare, Ireland. There are seven townlands in the parish. There are no large centres of population in the parish. Donadea is noted for its public forest park which is one of the most popular outdoor venues in both county Kildare and the west Dublin region. The nearest villages are Staplestown (4km distant) and Prosperous (7km distant). The parish name is derived from a church, traditionally said to have been founded by Saint Patrick. A small 17th-century church of the Church of Ireland, St Peter's, still exists within the Donadea demense.
The following are the townlands: Cooltrim North, Cooltrim South, Donadea, Donadea Demesne, Kilmurry, Kilnamoragh North and Kilnamoragh South.
The Normans came to Donadea in the 12th century and established a manor. The manor house was built on or close to the present castle. This structure was the first of many castles on the site throughout the Middle Ages. In 1558 the Aylmer family acquired the manor. In 1581, Gerald Aylmer commenced a new tower in Donadea which was not completed until 1624. It is now the oldest part of the Castle. In 1626, he repaired the medieval church. Gerald was ennobled as the first Baronet of Donadea.
The Book of Armagh records St Patrick’s visit to Dunmurraghill in 455, where he marked out the foundations for a religious settlement. The St. Peter’s site was laid out at the same time. The earliest churches were wooden in construction. The Danes destroyed Dunmurraghill in 832. The church at the St. Peter’s site was rebuilt by the Normans. In 1550 the Aylmer family of Lyons acquired the Manor of Donadea from the Earls of Ormond. In 1626 the first Aylmer baronet, Sir Gerald Aylmer, rebuilt the church. The Ecclesiastical Report of 1809 stated that: "the Church was in a tottering state but neat and clean.". It is now part of the Clane Union of Parishes. In the Catholic Church, the territory is part of the parish of "Clane and Rathcoffey" in the Roman Catholic Diocese of Kildare and Leighlin. The Church of St Patrick and St Brigidin is located in Clane while the Church of the Sacred Heart is located in Rathcoffey.