Engineer

An engineer constructed or repaired buildings and mechanical devices. There were a number of specialised types of engineers.

Omega was the stellar engineer who gave the Time Lords the source of power for time travel. (TV: The Three Doctors)

John Dyson was the supervising engineer at the Snowcap South Pole Base in 1986. He, Barclay and Ben Jackson used radiation to fight the Cybermen. (TV: The Tenth Planet)

Van Lutyens was an engineer at a Euro Sea Gas Control Rig. He fell under the weed creature's mental control, but was eventually freed thanks to the Second Doctor. (TV: Fury from the Deep)