The contents of the briefcase in Pulp Fiction are never explicitly revealed in the movie, and director Quentin Tarantino has stated that it is intentionally ambiguous. However, there are many theories and speculations about what could be in the briefcase. Some of the most popular theories include:

• Diamonds: The original script called for the briefcase to contain diamonds, but Tarantino decided against it since he had just used diamonds in a briefcase in the movie Reservoir Dogs.

• Marcellus Wallaces soul: Some fans believe that the briefcase contains Marcellus Wallaces soul, which is why he wears a bandage on the back of his neck.

• Elvis Presleys golden suit: According to one theory, the briefcase contains Elvis Presleys golden suit from the movie True Romance, which was also written by Tarantino.

• A light bulb: In one theory, the briefcase contains a light bulb, which represents enlightenment or knowledge.

• Whatever the viewer wants it to be: Tarantino has stated that the contents of the briefcase are "whatever you want it to be to advance the plot".

It is important to note that these are all just theories and speculations, and the true contents of the briefcase are never revealed in the movie.