William Tennent III (1740 – August 11, 1777) was a Presbyterian pastor and South Carolina politician. He was born and educated in northern Colonial America, but spent the latter part of his life in the southern state of South Carolina. He was a prominent advocate for the dis-establishment of any state religion. He is known for his opposition to British colonial policy, publishing patriotic essays in support of the revolution. He was selected to travel in 1775 into the "back county" of South Carolina to convert Loyalists to the cause. In the state assembly, he lobbied for religious liberty in the drafting of state constitutions.