The 1938 movie Bringing Up Baby featured Katharine Hepburn, Cary Grant and a leopard named Baby. In some scenes, the stars interacted with a live leopard on the set but for most of the film, special effects were employed to keep the actors and the animal apart. Mr. Grant was said to be especially nervous around the large cat.
This video runs close to seven and a half minutes and it isolates many of the tricks that were employed. If you don't want to know how it was done, don't click.
