Lord John Roxton was an associate of Professor Challenger as chronicled by Arthur Conan Doyle. Lord John Roxton, or Lord Roxton (Doyle and his collaborator Edward D. Malone use both titles interchangably despite their meaning separate things), is a sort of "Great White Hunter" figure, with widespread experience of far-off climes around the world. He takes great pride in his anti-slaving campaigns in South America. He is described as being the third son of the Duke of Pomfret.
In Tarzan Alive, Philip José Farmer reveals that Roxton is not the third son of a peer, and in fact has no claim to any titles at all. His baptismal names are given as John Byron Wentworth, and he is described as the illegitimate son of the 12th Baron Wentworth and Joane Clayton. His mother subsequently married the 14th Duke of Denver by whom she had at least two legitimate sons; the Duke also adopted John. Roxton is thus great-half-uncle of Lord Peter Wimsey.
In the Westerns of J.T. Edson, Lord John Roxton is described, somewhat improbably, as the son of Lord James Roxton. In Gary Chaloner's Red Kelso webcomic, Lord John Roxton is the father, equally-improbably, of Lord John "Lord Jack" Roxton, Jr.