Gaffer

In film production: The chief or head electrician or supervisory lighting technician in the film/photography crew on a movie set. The gaffer is responsible for the design and execution of a production's lighting plan on the set. The gaffer's right-hand assistant is known as the best boy. Gaffer tape refers to multi-purpose, sticky and wide black or gray cloth tape, used to mark studio floors, to hold things together, etc. Gaffer tape is also known as duct tape. [Source: Filmsite.org]