Filet mignon is a cut of beef that comes from the small end of the tenderloin, which is located near the spine of the cow. The tenderloin is the most well-known muscle on a cow and is also the most tender, making filet mignon one of the most prized cuts of beef. It is a lean cut of meat that is often considered the best-tasting part of a cow. Due to the small amount of filet mignon that can be butchered from each animal, it is generally considered one of the most expensive cuts of beef.