William of Orange, was a champion of Protestantism at a time when revocation of the Edict of Nantes was leading to bitter persecution of thousands of innocents under attack from Catholic Louis XIV (the Sun King) and others. In 1686, William saved the Waldensians from historical obliteration, funding their Glorious Return to reclaim their valleys after a brave and bitter resistance supported by miraculous escapes at night from the army of Louis XIV and Savoy. For this alone, he is celebrated to this day in the Waldensian valleys.
This act was 'rewarded' by his own bloodless Glorious Revolution in 1688 when he become William III, King of England, by sailing over from Holland and deposing, with full support of the nobility and the people, James II, his Catholic uncle, who fled to Paris.
An outstanding international statesman, William of Orange is buried in the Stuart Vault under the floor of the Henry VII Chapel in Westminster Abbey. A grand memorial to him and Queen Mary was planned, but never built. He lies next to his other uncle, King Charles II and his own wife, Queen Mary (Stuart) who was also his first cousin. William III was grandson of Charles 1st who was beheaded by Cromwell which makes his own keen Protestantism slightly surprising.
See : The tomb of William of Orange (bottom of the list on the link)