William Lowther JP DL was a British diplomat and Conservative politician who sat in the House of Commons from 1868 to 1892.

William Lowther, 1st Earl of Lonsdale, KG, also known as Sir William Lowther, 2nd Baronet, of Little Preston, from 1788 to 1802, and William Lowther, 2nd Viscount Lowther, from 1802 to 1807, was a British Tory politician and nobleman known for building Lowther Castle.