Chang (Dark Water)
From Tardis Wiki, the free Doctor Who reference
Dr. Chang was charged with maintaining the Mausoleum in St. Paul's Cathedral. He took care of the Twelfth Doctor and Clara Oswald when they were sightseeing in the Mausoleum and showed them 3W. He was then one who showed them Dark Water and what the 3W stood for. He also created an online link between Clara and Danny Pink. Despite his pleas, the Master killed him. (TV: Dark Water)
