Robert Cullen, Lord Cullen FRSE (1742–1810) was a Scottish judge. He played a key role, along with his father William Cullen, in obtaining a royal charter for the Philosophical Society of Edinburgh, resulting in the formation of the Royal Society of Edinburgh in 1783.
Born on 22 September 1742, in Edinburgh, the son of eminent physician and chemist William Cullen and Anne Johnstone (d.1786), Robert was educated at Edinburgh University. His brother was the physician Henry Cullen.
He was admitted to the Faculty of Advocates in 1764, and served as a Senator of the College of Justice (1796-9), and as Lord of Justiciary (1799–1810).