Ernest Howard Griffiths (15 June 1851 – 3 March 1932) was a British physicist born in Brecon, Wales.
He was elected a Fellow of the Royal Society in 1895 and won its Hughes Medal in 1907.
On his maternal side he was a descendant of the 17th-century admiral Robert Blake.
Griffiths was appointed principal of the University College of South Wales and Monmouthshire, Cardiff in 1901 and given a professorship in experimental philosophy.
He was a Fellow of Jesus College, Oxford in 1905, 1909, 1913, and 1917, as part of a system whereby a college fellowship rotated amongst the principals of Welsh university colleges.