What famous underwater explorer was responsible for developing the trademarked "AQUA LUNG"?

Jacques Cousteau, the world renowned underwater explorer along with efforts of Emile Gagnan redesigned a car regulator in 1942.  The two were able to provide divers with decompressed air even with a small intake of air.  Trademarked as the “Aqua Lung”, this device became known as the first dive tank for breathing underwater.