William Maitland of Lethington (1525 – 9 June 1573) was a Scottish politician and reformer, and the eldest son of poet Richard Maitland.
William was the renowned 'Secretary Lethington' to Mary, Queen of Scots. As Secretary of State, he played a prominent part in the various movements of his time, but gained the confidence of no party. He adhered to the party of James Stewart, 1st Earl of Moray, illegitimate half-brother of the Queen, against the extreme measures of John Knox.
Maitland proved a highly astute ambassador at Elizabeth I of England's court. He was involved in the conspiracy to murder David Rizzio (the private secretary and rumoured lover of Queen Mary) by her King consort Henry Stuart, Lord Darnley and his supporters. But he managed to regain the Queen's favour. After Mary was captured by her enemies at the battle of Carberry Hill, on 25 July 1567 Maitland came to see the English ambassador in Edinburgh, Nicholas Throckmorton. As instructed by Elizabeth, Throckmorton asked Maitland if the plan was to restore Mary to the throne. If so, Elizabeth promised to help prosecute Darnley's murder and preserve Prince James. Throckmorton recorded Maitland's personal answer, which outlined that English interference was not welcome at this time, and might even be counterproductive, and Throckmorton would not be allowed to see Mary;
"Being in place to knowe more than you can knowe, I saye unto yowe ..., in case you doe on the Quenes majesties behalf your mestris, presse this company to enlarge the Quene my soveraigne, and to suffer you to goe unto her (at Lochleven Castle), or doe use any thretnynge speache in those matters, the rather to compasse them (rather than achieve them), I assure you, you wyll put the Quene my soveraigne in greate jeopardye of her lyffe: and therefore there is none other waye for the present to do her good but to give place and use mildness."