This is a Skywalker Sound sound effect created by Ben Burtt for the Rancor in Star Wars: Episode VI - Return of the Jedi (1983). It should not be confused with both Sound Ideas, ELEPHANT - VARIOUS SNORTS, GROWLS, TRUMPETS, ANIMAL and Jurassic Park, T-Rex - Exclamation Roar, which were also used for the roars of the Rancor. Links: https://soundeffects.fandom.com/wiki/SKYWALKER,_ROAR_-_RANCOR_ROAR#Audio_Samples