A film must have actors, as well as other talent depending on the style of the film. This might include narrators, dancers, puppeteers or stunt doubles. The person in charge of finding all of these people is called the casting director.
In addition to the director, a film also has a producer, or a team of producers. The producer is in charge of running the financial and technical end of things, and often works closely with the director to obtain a shared vision for the film.
A film will have at least one cameraman, as well as a Director of Photography, known as the DP. The DP is in charge of cinematography. The director guides the actors, but it is often the DP that sets up the actual shot. The DP will work with the lighting crew (the electricians and the grips) to ensure the proper mood for each scene.
Costume and set designers work together with the director to build the world of the film by choosing complementary outfits and sets.
Many people on film sets go completely unnoticed. There are caterers, custodians and personal assistants who work tirelessly behind the scenes, and are usually not recognized for their vital contributions.