Way back in 1951 an obscure cowboy in an obscure movie was killed by an indian. The scream the sound engineers used in that scene went on to over 200
other movies, some you will have seen. The scream even gained a name, "Wilhelm scream" in honour of that first 2 bit part.
Here is it in a compilation of movie scenes
Much more on this scream, and the presumed "screamer" Sheb Wooley can be found in this great article.