Richard Slater Milnes (December 1759 – 2 June 1804) was an English heir, landowner and politician.

The heir to a cloth fortune, he served in the British Parliament, where he championed the abolitionist cause.

He served as a Member of Parliament for the City of York in the House of Commons of Great Britain from 1784 to 1790, and again from 1790 to 1802.

During his tenure, he gave a speech in favour of the abolition of the slave trade and was a supporter of William Pitt the Younger.

[1] He was succeeded by his eldest son Robert Pemberton Milnes who also became an MP, representing Pontefract.