John Pennington, 1st Baron Muncaster (c. 1740 – 8 October 1813), known as John Pennington until 1783, was a British peer and Tory politician.
Muncaster was returned to Parliament as one of two representatives for Milborne Port in 1781, a seat he held until 1796, and then sat for Colchester until 1802. In 1806, he was returned for Westmoreland, and sat for the county until he died in 1813. In 1783, ten years before he succeeded his father in the baronetcy, he was elevated to the Peerage of Ireland as Baron Muncaster, with remainder in default of male issue of his own to his younger brother Lowther Pennington and the heirs male of his body.
Lord Muncaster married Penelope, daughter of James Compton, in 1778. She died in November 1806. Muncaster survived her by seven years and died in October 1813. He had no sons and was succeeded in the baronetcy and barony (in the barony according to the special remainder) by his younger brother, Lowther.