An undertaker was a person who prepared dead bodies for burial. Albar Prentis was Tivoli's undertaker, and he took the supposedly dead body of the Fisher King to Earth. (TV: Before the Flood) Even when he was a ghost, Prentis's undertaker clothes still remained. (TV: Under the Lake/Before the Flood)
The Shansheeth were known as "galactic undertakers." (TV: Death of the Doctor)
As the citizens of Mercy expected him to die, an undertaker kept trying to measure the Eleventh Doctor. (TV: A Town Called Mercy)
Gwen Cooper and Rhys Williams disguised themselves as undertakers in order to rescue Captain Jack Harkness. (TV: Childen of Earth: Day 2)