Rev Prof Humphrey Lloyd DD FRS FRSE MRIA (1800–1881) was an Irish physicist.
He was Erasmus Smith's Professor of Natural and Experimental Philosophy at Trinity College Dublin (1831-1843) and much later Provost (1867–1881).
Lloyd is known for experimentally verifying conical refraction, a theoretical prediction made by William Rowan Hamilton about the way light is bent when travelling through a biaxial crystal.
He was a Fellow of the Royal Society, and President of both the British Association and the Royal Irish Academy.