1649
Charles I (1600-49) of the Stuart dynasty was the last man to be canonised by the Church of England. There had been other English kings known as saints before him (e.g., St Edmund, St Edward the Martyr and St Edward the Confessor) but he may have been the most incompetent ruler to be given that honour.
Coming to the thrones of England, Ireland and Scotland in 1625, Charles inherited a history of bad relations between the crown, the English Parliament, and the Scottish church. A more flexible or far-sighted monarch might have saved himself from catastrophe but Charles was stubborn, short-sighted and untrustworthy. He tried to impose episcopacy on the Calvinist Scots; his religious leanings in England and his marriage to a French princess made many fear he was sponsoring a return to Catholicism; and his refusal to consult Parliament for over a decade led directly to the English Civil War.
Defeated in war, he was put on trial by his Parliamentarian captors, accused of treason. “[W]icked designs, wars, and evil practices of him, the said Charles Stuart, have been, and are carried on for the advancement and upholding of a personal interest of will, power, and pretended prerogative to himself and his family, against the public interest, common right, liberty, justice, and peace of the people of this nation.” He was found guilty and condemned to death. Charles behaved bravely on the block, though he broke with conventional piety by refusing to pardon his executioner. (The painting above is of his arch-enemy Cromwell peering into the royal coffin.)
For his personal religious faith, which was unquestionably deep, and his defence of the Church of England, Charles was regard as a martyr and canonized by Convocation on the restoration of the monarchy in 1660.