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.

|- style="text-align: center;" | width="30%" |Preceded by:
In Commission | width="40%" style="text-align: center;" |Lord Privy Seal
1692–1699 | width="30%" |Succeeded by:
The Viscount Lonsdale

|- style="text-align: center;" | width="30%" |Preceded by:
The Duke of Leeds | width="40%" style="text-align: center;" |Lord President of the Council
1699–1702 | width="30%" |Succeeded by:
The Duke of Somerset

|- style="text-align: center;" | width="30%" |Preceded by:
The Duke of Somerset | width="40%" style="text-align: center;" |Lord President of the Council
1702–1708 | width="30%" |Succeeded by:
The Lord Somers

|- style="text-align: center;" | width="30%" |Preceded by:
The Duke of Ormonde | width="40%" style="text-align: center;" |Lord Lieutenant of Ireland
1707–1708 | width="30%" |Succeeded by:
The Earl of Wharton

|- style="text-align: center;" | width="30%" |Preceded by:
HM Queen Anne | width="40%" style="text-align: center;" |Lord High Admiral
1708–1709 | width="30%" |Succeeded by:
The Earl of Orford
(First Lord of the Admiralty)