Filet mignon is a cut of meat from the beef tenderloin. You can cook up a whole roasted beef tenderloin for a fancier meal or to serve more people. Because the beef tenderloin is a tapered muscle, the wider end is served as the classic French "Chateaubriand" while smaller slices from the tapered end are what we typically consider "filet mignon" - "mignon" means little in French. Beef tenderloin is also sliced thinly, dressed, and served as Beef Carpaccio.