Chang (Dark Water)
From Tardis Wiki, the free Doctor Who reference
Dr. Chang was a Doctor charged with maintaining the Mausoleum in St. Paul's Cathedral. He took care of the Doctor and Clara Oswald when they were sightseeing in the Mausoleum and showed them 3W. He also created an online link between Clara and Danny Pink.
Dr. Chang was murdered by The Master. (TV: Dark Water)
