William Alexander, Earl of Stirling (c. 1570, Menstrie, Clackmannanshire - 1640) was a Scotsman who was an early developer of Scottish colonisation of Nova Scotia.

When a young man he was appointed tutor to the Earl of Argyll and accompanied him abroad. At a later date he received the place of gentleman usher to Prince Charles, son of James VI of Scotland, and continued in favour at court after the king became James I of England. He attained reputation as a poet and writer of rhymed tragedies, and assisted the king in preparing the metrical version known as "The Psalms of King David, translated by King James," and published by authority of Charles I. He was knighted in 1614. In 1621 King James I granted him a royal charter appointing him governor of a vast territory in North America which was erected into a lordship and barony of Nova Scotia (New Scotland); the area now known as Nova Scotia, New Brunswick, and part of the northern United States. The creation of Baronets of Nova Scotia was used to settle the plantation of the new province.

Alexander was an active promoter of his New Scotland and brought many British settlers to the maritimes. He was appointed Secretary for Scotland in 1626 and held that office for the rest of his life. In 1630, King Charles rewarded his service by creating him Viscount of Stirling and in 1633 he became Earl of Stirling.

Lord Stirling’s efforts at colonisation were less successful, at least from a monetary standpoint. He spent his fortune, and when the maritimes were returned to France in 1632, it was lost. He spent his later years with limited means, and died in London on September 12, 1640.

Stirling also wrote closet dramas: classical tragedies titled Croesus, Darius, The Alexandrean, and Julius Caesar. His plays were published in several editions (1604, 1607, 1616, 1637).

There is an icebreaker of the Royal Canadian coast guard named after him.