William Lobb (1809 – 3 May 1864) was a Cornish plant collector, employed by Veitch Nurseries of Exeter, who was responsible for the commercial introduction to England of Araucaria araucana (the monkey-puzzle tree) from Chile and the massive Sequoiadendron giganteum (Wellingtonia) from North America.
He and his brother, Thomas Lobb, were the first collectors to be sent out by the Veitch nursery business, with the primary commercial aim of obtaining new species and large quantities of seed. His introductions of the monkey-puzzle tree, Wellingtonia and many other conifers to Europe earned him the sobriquet "messenger of the big tree". In addition to his arboreal introductions, he also introduced many garden shrubs and greenhouse plants to Victorian Europe, including Desfontainia spinosa and Berberis darwinii, which are still grown today.
Lobb was born in 1809 at Lane End, Washaway near Bodmin Cornwall and spent his early life at Egloshayle, near Wadebridge. He had four brothers and two sisters. Two of the brothers, Henry and James, became managers of gunpowder plants in south-west England. His father, John Lobb, was the estate carpenter at nearby Pencarrow where a notable garden had been developed by Sir William Molesworth. John developed a love of gardening and, after losing his place at Pencarrow, he took up employment at Carclew House, near Falmouth, the home of Sir Charles Lemon. Sir Charles would later be amongst the first people in England to receive and grow rhododendron seed from Sir Joseph Hooker, who had sent seed directly to Sir Charles from his Himalayan expedition of 1848–1850.