The Mouthpiece is a 1930 crime play by the British writer Edgar Wallace. It was one of several theatrical failures written by Wallace following the enormous success of On the Spot, with a plot described as "flimsy".
It ran for twelve performances at Wyndham's Theatre in the West End. The cast included Emlyn Williams, Douglas Payne, Mabel Terry-Lewis and Margaret Bannerman. In 1935 it was posthumously novelised by Robert Curtis.
A gang of criminals discover that a young woman is unaware that she is about to inherit a fortune, and scheme to marry one of their members to her to get their hands on the money.