1. n. 
The supervisor of the rig crew. The driller is responsible for the efficient operation of the rigsite as well as the safety of the crew and typically has many years of rigsite experience. Most drillers have worked their way up from other rigsite jobs. While the driller must know how to perform each of the jobs on the rig, his or her role is to supervise the work and control the major rig systems. The driller operates the pumps, drawworks, and rotary table via the drillers console—a control room of gauges, control levers, rheostats, and other pneumatic, hydraulic, and electronic instrumentation. The driller also operates the drawworks brake using a long-handled lever. Hence, the driller is sometimes referred to as the person who is "on the brake."