William Russell, 1st Baron Russell of Thornhaugh

William Russell, 1st Baron Russell of Thornhaugh (c. 1558–1613) was an English military leader.

Russell was a younger son of the 2nd Earl of Bedford. Due to conflicting records, Russell's birthdate is uncertain. Some evidence indicates he was born as early as 1553; others as late as 1562.

Russell began his active military career serving in the Netherlands. He was noted for maintaining an effective fighting force under difficult circumstances.

In 1594, Russell was appointed Lord Deputy of Ireland. Ireland was in a state of uprising and there were two opinions on how to bring peace. One faction wanted to negotiate with the Irish leaders; the other, which included Russell, favoured ending the uprising with military force. The latter faction prevailed, and the Nine Years War was ended in 1603. During his time in Ireland, Russell fell into dispute with his chief military commander, Sir John Norris, and was recalled to England in 1597, his greatest achievement having come with the defeat and death of the rebel Fiach MacHugh O'Byrne in the same year.

In 1599, Russell was named as leader of the forces defending western England in anticipation of a Spanish invasion. However, the invasion plans were thwarted.

Russell, having lost influence in the royal court, retired to his estates. He died on August 9, 1613.