William Colyear, 3rd Earl of Portmore

William Charles Colyear, 3rd Earl of Portmore (1745–1823) was a Scottish peer, styled Viscount Milsington until 1785.

He was the second but only surviving son of Charles Colyear, 2nd Earl of Portmore. He was styled Viscount Milsingtion in 1756 on the death of his brother David.

Milsington was educated at Eton and St John's College, Cambridge. In 1774, he unsuccessfully contested Evesham as a Tory.

His grey mare, Tiffany, won the 50 l. weight-for-age race at Salisbury Races in 1780.

He succeeded as the 3rd Earl of Portmore in 1785 and married Mary (1753–99), second daughter of the 10th Earl of Rothes.

He died in London in 1823 and was succeeded by his son Thomas Charles Colyear, 4th Earl of Portmore.