William C Carruthers FRS (29 May 1830 – 2 June 1922) was a Scottish botanist.
Carruthers was keeper of the Botanical Department at the Natural History Museum from 1871 to 1895. He was consulting botanist to the Royal Agricultural Society (1871–1909).
Hand-written letter from Carruthers in 1883, to James Bain
He was born in Moffat, Dumfriesshire, the son of merchant Samuel Carruthers. Educated at Moffat Academy, he graduated from Edinburgh University. He married in 1865 Jeanie, daughter of William Moffat, architect, of Edinburgh.
He was elected Fellow of the Royal Society in 1871.  He was president of the Linnean Society from 1886 to 1890, and a member of the Botanical Society of Edinburgh.