From the Dictionary of National Biography...

CARSEWELL, JOHN (fl. 1560–1572), bishop of the Isles, was in his earlier years chaplain to the Earl of Argyll and rector of Kilmartin. When the assembly of the kirk, on 20 July 1560, appointed superintendents of the various districts of Scotland, Carsewell was appointed superintendent of Argyll and the Isles (Knox, Works, ii. 87; Calderwood, History, ii. 11). He was also dean of the Chapel Royal of Stirling (Keith, History, Appendix, p. 128). In his capacity of superintendent of Argyll he was appointed by the assembly, in 1567, to ‘take satisfaction’ from Argyll for separation from his wife, and for ‘other heinous offences’ (Calderwood, ii. 397). In July 1569 he was rebuked by the assembly for accepting the bishopric of the Isles, and for attending a parliament ‘holden by the queen after the murther of the king’ (ib. ii. 491). He died some time before 20 Sept. 1572.

[Keith's Scottish Bishops, 307–8; Calderwood's History of the Church of Scotland., vols. ii. and iii.]