Agnes Guppy-Volckman (1838-1917) was a British spiritualist medium. She was born Agnes Elisabeth White in Regent's Park, London. She was known as Miss Agnes Nichol, later becoming the second wife of the spiritualist Samuel Guppy in 1867. After the death of Guppy in 1875, she married William Volckman. John Grant has written that she "was a clever charlatan; her stunts bear all the hallmarks of extravagant stage conjuring tricks." Molly Whittington-Egan has written a biography of Guppy-Volckman.