Charles Walmesley, O.S.B. (best known by the pseudonyms Signor Pastorino or Pastorini; 13 January 1722 – 25 November 1797) was the Roman Catholic Titular Bishop of Rama and Vicar Apostolic of the Western District of England. He was known, especially in Ireland, for predicting the downfall of Protestantism in 1821–5 and the triumphant emergence of the Catholic Church.
He was the fifth son of John Walmesley of Westwood House, Wigan, Lancashire; was educated at the English Benedictine College of St. Gregory at Douai (now Downside School, near Bath); and made his profession as a Benedictine monk at the English Monastery of St. Edmund, Paris (now Douai Abbey, near Reading), in 1739. Later he took the degree of D.D. at the Sorbonne.
Walmesley's scientific attainments soon brought him into notice as an astronomer and mathematician. He was consulted by the British Government on the reform of the calendar and introduction of the "New Style" in 1750-52, and was elected a Fellow of the Royal Society of London, and the kindred societies of Paris, Berlin, and Bologna.
From 1749 to 1753 Walmesley was Prior of St. Edmund's Priory in Paris and in 1754 was sent to Rome as procurator general of the English Benedictine Congregation. Two years later he was selected by Propaganda Fidei as coadjutor bishop, with right of succession, to Lawrence William York, the Vicar Apostolic of the Western District; and was consecrated Bishop of Rama on 21 December 1756. He administered the vicariate after York's retirement of York in 1763, and succeeded that prelate on his death in 1770.