I believe that was Pope Adrian IV who in a Papal Bull gave Ireland to Henry II, then King of England.
It is interesting to note that the claim of Adrian IV., here advanced, to jurisdiction over all islands was founded, as we learn from John of Salisbury, on the forged donation of Constantine (v. Book iii. No. iii.). Urban II. had disposed of Corsica under the same pretension. Lord Lyttleton in his still valuable History of Henry II. (vol. v. p. 67) speaks as follows concerning this whole transaction: "Upon the whole, therefore, this bull, like many before and many since, was the mere effect of a league between the papal and regal powers, to abet and assist each other's usurpations; nor is it easy to say whether more disturbance to the world, and more iniquity, have arisen from their acting conjointly, or from the opposition which the former has made to the latter! In this instance the best, or indeed the sole excuse for the proceedings of either, was the savage state of the Irish, to whom it might be beneficial to be conquered, and broken thereby to the salutary discipline of civil order and good laws."from The Bull of Pope Adrian IV Empowering Henry II to Conquer Ireland. A.D. 1155