The Shrek we all know from the movies is voiced by a Scottish-accented Mike Myers. However, the part originally went to fellow SNL cast member Chris Farley before his untimely death in 1997. Apparently, 90% of the dialogue was recorded, but DreamWorks decided to scrap both the audio and the original script to start over again. After a quick rewrite they brought on Myers to voice the ogre, and the movie debuted in 2001.
This unused audio was mostly unheard until recently when producer John Garbett shared this clip on YouTube.
[h/t: Laughing Squid]