In the 1920's, Volney Phifer was Hollywood's premier animal trainer and his most successful protégé was Leo, the MGM lion, who Volney taught to roar on cue.
The original logo was designed by Howard Dietz and used by the Goldwyn Pictures Studio studio from 1916 to 1924; since then there have been around five different lions used for the iconic logo.
Jackie (above) was the first lion whose roar was heard by audiences of the silent film era, via a gramophone record. She first growled softly; this was followed by a louder growl, a brief pause, and then a final growl, before looking off to one side.
And therein lies the strength of an enduring logo: I can hear her roar right now...as I know you can.