A derrick is a lifting device designed for moving large objects. They are used widely in engineering, and to drill for oil and gas reserves. Thomas Derrick was a hangman in Elizabethan England, and was a convicted rapist who was facing the death penalty.
Derrick was offered a pardon by the Earl of Essex, if he worked for the state as an executioner. During his time as a hangman, he designed a new system with a topping lift and pulley, as opposed to the rope over a beam method. Derrick executed over 3,000 people. One of whom, rather ironically, was The Earl of Essex, the man who pardoned him.