William Leo Franklyn (né Beare; 22 September 1925 – 31 October 2006) was an English actor, perhaps best known for voicing the "Schhh... You Know Who" adverts for Schweppes from 1965 to 1973.

The young Franklyn attended Wesley and Haileybury Colleges, both in Melbourne, and developed an abiding love of cricket.

He also became a leg spinner, and ran his own team, the Sargentmen, raising money for the Malcolm Sargent Cancer Fund for Children.

He played Jacques Fleury in The Adventures of the Scarlet Pimpernel (1955–56) and Peter Dallas in the spy drama series Top Secret (1961–62), and also appeared in several episodes of The Avengers.

He was featured on This Is Your Life (1978), appeared in the 1984 comedy television series The Steam Video Company, and in G.B.H.

He voiced Danger Mouse in the unbroadcast pilot for the British television series (although David Jason replaced him in all broadcast episodes).

In 2004 and 2005 he took over the role of "The Book" (the narrator) from his friend Peter Jones for the third, fourth and fifth radio series of The Hitchhiker's Guide to the Galaxy.