The Make-up Artist (or MUA) is a specialist role. They are in charge of the Hair and Makeup for the actors.
They may also be in charge of Special Effects (SFX), such as blood, gun shots, and bruising. This would make them an SFX MUA.
The MUA works with the Director to ensure the look of the film. In larger films, they can be their own department. In Action On The Side films, they work under the Art Director