Sir Leoline Jenkins (1625 – 1 September 1685) was a Welsh academic, jurist and politician. He was a clerical lawyer serving in the Admiralty courts, and diplomat involved in the negotiation of international treaties (e.g. Nimègue).
He was originally from Cowbridge in south Wales, son of Leoline (an anglicisation of Llewellyn) Jenkins, a small landowner. He went to school in Cowbridge and then to Jesus College, Oxford. As Principal of Jesus College from 1661 to 1673, he was responsible for much construction work, including the college library. The position was one of several rewards he received from King Charles II of England for his loyalty to the Royalist cause during the English Civil War; he was also created a judge. As Judge of the Admiralty he won Samuel Pepys' warm praise for his ability and integrity.
Jenkins was made a privy counsellor in February 1680. He served as Secretary of State for the Northern Department from 26 April 1680 to 2 February 1681 and Secretary of State for the Southern Department from 2 February 1681 to 14 April 1684. His major achievements include authoring the Statute of Frauds (29 Car. II c. 3) and the Statute of Distributions (22 & 23 Car. II, c. 10), dealing with the inheritance of personal property. Whilst Secretary of State, he was served by the Welsh lawyer (and former student of Jesus College) Owen Wynne, who has been called "an early example of the permanent civil servant."