William Parsons, 3rd Earl of Rosse (17 June 1800 – 31 October 1867) was an
Anglo-Irish astronomer who had several telescopes built. His 72-inch telescope, built in 1845 and colloquially known as the "
Leviathan of Parsonstown", was the world's largest telescope, in terms of aperture size, until the early 20th century. From 1807 until 1841, he was
styled as
Baron Oxmantown.