Sir Francis Walsingham was Elizabeth's Principal Secretary from 1573 until 1590 and has gone down in history as her 'spymaster', although intelligence gathering was only one of his functions as a trusted courtier close to the Queen.
He did establish an intelligence network that stretched across Europe and right into the heart of Spanish military strategies, and he did foil the various conspiracies to overthrow Elizabeth, including one involving Mary, Queen of Scots that he used to secure her execution. But as one of Elizabeth's trusted courtiers he worked on various foreign and domestic affairs of state, as well as being one of the first politicians to have the vision to see England's potential as a maritime power.
Educated at Kings College, Oxford, like other prominent Protestants, he fled to Europe upon Mary's succession, returning on Elizabeth's. Through the offices of William Cecil, Elizabeth's Chief Advisor, he became MP first for Banbury in 1559, then for Lyme Regis in 1563. He was knighted in 1557 and was used as her ambassador by Elizabeth and died in 1590, not as wealthy as might have been expected for one whom the Queen rewarded for his services.
Sir Francis Walsingham was a powerful and intriguing character and has been portrayed many times, sometimes sympathetically, sometimes not. In this clip from Elizabeth Geoffrey Rush plays a ruthless Walsingham, ready, and able, to kill when necessary.