The driller is a team leader in charge during the process of well drilling. The term is commonly used in in the context of an oil well drilling rig.

The driller is in charge of his crew, and running the rig itself. Most of the time, his job is simply to monitor the rig's activity, while the automatic driller runs the breaks and drills the hole. The driller is responsible for interpreting the signals the well gives regarding gas and fluids with high pressure. In an emergency he is also responsible for taking the correct counter measures to stop an uncontrolled well control situation from emerging. The driller will watch for gas levels coming out of the hole, how much drilling mud is going in and other information. While tripping, the driller will run the floor and work the rig.