Thomas Herbert, 8th Earl of Pembroke, 5th Earl of Montgomery (c. 1656-1733), was a British politician during the reigns of William III and Anne.

From 1690 to 1692 he was First Lord of the Admiralty; then he served as Lord Privy Seal until 1699, being in 1697 the first plenipotentiary of Great Britain at the congress of Ryswick.

On two occasions he was lord high admiral for a short period; he was also lord president of the council and Lord Lieutenant of Ireland, while he acted as one of the lords justices seven times; and he was president of the Royal Society in 1689-1690.

The peerages were inherited by his son, Henry.