Robert Clayton (1695–1758) was an Irish Protestant bishop, now known for his Essay on Spirit. In his own lifetime he was notorious for his unorthodox beliefs, which led his critics to question whether he could properly be called a Christian at all, and at the time of his death he was facing charges of heresy.
Clayton was born at Dublin in 1695, a descendant of the Claytons of Fulwood, Lancashire, whose estates came to him by inheritance. He was the eldest of eight children of Dr. Robert Clayton, minister of St. Michael's Church, Dublin, and dean of Kildare, and Eleanor, daughter of John Atherton of Busie. Zachary Pearce educated him privately, at Westminster School.
Clayton entered Trinity College, Dublin, became B.A. 1714, a fellow the same year, M.A. 1717, LL.D. 1722, and D.D. 1730. He made a tour of Italy and France, and on his father's death in 1728 came into possession of a good estate and married Katherine, daughter of Lord Chief Baron Nehemiah Donnellan and his second wife Martha Ussher. He gave his wife's fortune to her sister Anne (who used it to fund the Donnellan Memorial Lectures at Trinity College), and doubled the bequest, under his father's will, to his own three sisters. A wealthy man, he lived in Dublin in what is now Iveagh House. One of the two houses (No. 80) that make up the current Iveagh House was designed for Clayton by Richard Castle, and built in 1736–7.
A gift to a distressed scholar recommended to him by Samuel Clarke brought him Clarke's friendship. Clayton embraced Clarke's Arian doctrines and held to them through life. Queen Caroline, hearing from Clarke of Clayton, had him appointed bishop of Killala and Achonry in 1729-1730. In 1735 he was translated to the diocese of Cork and Ross, and in 1745 to the diocese of Clogher. In 1752 he was made Fellow of the Society of Antiquaries, having some years before been elected a Fellow of the Royal Society.