John Lowther, 1st Viscount Lonsdale (1655 – July 1700), was an English politician, created Viscount Lonsdale in 1696.

Before this creation John had succeeded his grandfather, another Sir John Lowther (d. 1675), as a baronet, and had been member of parliament for Westmorland from 1675 to 1696. In 1688 he was serviceable in securing Cumberland and Westmorland for King William III; in 1690 he was first lord of the treasury, and he was Lord Privy Seal from March 1699 until his death.

Lonsdale wrote Memoirs of the Reign of James II, which were printed in 1808 and again in 1857. His family became extinct when his son Henry, the 3rd viscount (1694-1751), died unmarried in March 1751.

|- style="text-align: center;" | width="30%" |Preceded by:
The Earl of Pembroke and Montgomery | width="40%" style="text-align: center;" |Lord Privy Seal
1699–1700 | width="30%" |Succeeded by:
The Earl of Tankerville