Edinburgh merchant and banker.
Heavily involved in the tobacco trade. During the financial panic of 1772 Franklin lent large sums to William and Robert Alexander. By 1775 William Alexander was bankrupt and in debtors prison, but managed to repay his loan from Franklin.
During the Revolutionary War, Alexander lived first in Dijon (1776-77) and later in Paris (1778-79) where he remained on intimate terms with Franklin while at the same time accepting payment from the British for providing information about the American diplomatic mission in France. Because Alexander’s chief British contacts seem to have been pro- American, and because Franklin seems to have been somewhat aware of Alexander’s activities, his work may be more accurately described as communication than espionage.
Settled in Virginia in 1783.
Brother of Alexander John and Robert; father of William Jr., Robert, Bethia, Christine, Jane, and Mariamne (who married Jonathan Williams, Jr), among other children.