Leslie (Lesley), Robert (d. 1672), Church of Ireland bishop, was eldest son of Henry Leslie (qv), later Church of Ireland bishop of Down and Connor and subsequently of Meath, and his wife Jane Swinton. His early life remains obscure, but he graduated BA from TCD on 23 March 1637, and MA from Aberdeen on 16 July 1638. Of similar theological views to his father, Leslie served as prebendary of Rasharkin (1638–61), holding the office nominally during the interregnum. He was incorporated at Oxford on 13 June 1639. He received the degree of DD, though when, and from where, remains unclear.
To avoid persecution under the commonwealth, Leslie went into exile in America, spending much of the interregnum in Virginia. However, a petition (c.1657) sought to have him appointed as a minister in the barony of Lecale. Leslie held a grant of the mesne profits of the diocese of Dromore during this period. After the restoration, on 6 August 1660 he was nominated as bishop to the vacant see of Dromore, and on 10 August he was appointed archdeacon of Connor, holding the post in commendam until 1671. He was one of eleven bishops consecrated in Dublin by John Bramhall (qv) on 27 January 1661. However, on 29 April he was translated to Raphoe (letters patent of 20 June 1661) in succession to John Leslie (qv).
As bishop of Raphoe, Leslie took a hard line with dissenters. At first, in September 1661 he did not consider their activities in his diocese to be an issue, but his attitude soon changed. In November he complained to Bramhall about the increase in nonconformist activity (especially preaching) in the diocese, requesting the despatch of a unit of cavalry to assist in restoring order. On 22 November 1661 he petitioned for the restitution of his jurisdiction, and for leave of absence from parliament until his diocese was in a more orderly condition. In February 1662 he sought instructions from Bramhall on how best to deal with dissenters, particularly whether he should have presbyterian ministers prosecuted at the local assizes or in Dublin; his own preference was for the latter. However, he bowed to pressure from Dublin for leniency in such matters. Leslie believed that the question of nonconformist activity was unlikely to be dealt with until the arrival of James Butler (qv), duke of Ormond, as lord lieutenant in 1662. Throughout the 1660s he continued to advocate a harsher line, having four presbyterian ministers incarcerated (1664), and attempting (1670) to persuade Roger Boyle (qv), bishop of Down and Connor, to do likewise. Leslie's activities prompted interventions by Sir Arthur Forbes (qv) on behalf of dissenters in the diocese. Leslie was subsequently appointed bishop of Clogher; letters patent for his translation to the diocese were issued on 26 August 1671. On 15 September he was granted the sinecure archdeaconry of Clogher in commendam; the profits were to be used to construct an episcopal residence in the diocese. Robert Leslie died 10 August 1672 in Ballygawley. He was buried in Clogher cathedral.
Leslie married Nichola, daughter of Sir Francis Hamilton of Castle Hamilton, Co. Cavan. They had one daughter, Jane.