Hubert Rejk is minor villain in The Witcher 3: Wild Hunt.
Hubert Rejk works as a coroner and he is a fundamentalist serial killer dedicated to the Order of the Eternal Fire as he shares their belief that Novigrad is a fallen city. Targeting people he believes have blasphemed against his religion, the Concerned Citizen performs brutal torture on his victims by removing their eyeballs and placing burning coals within their empty sockets, forcing them to drink formaldehyde, and cutting out their hearts. He believes these horrific murders will act as a form of shock treatment, awakening the city to it's decline and causing its populace to repent.
He first comes to Geralt's attention after brutally assaulting and nearly murdering his friend, the bard, Priscilla. Other victims include a lecherous dwarf, a lecturer on theology who criticized the Church, an old woman who had a crisis of faith after witnessing the church burn people alive, beggars, street walkers, and orphan children.
When Geralt gets too close to the truth, he frames another for his crimes and should Geralt fall for the ruse, the killer leaves behind a final body and a mocking note detailing how he's going to move on to a smaller village and continue his work. Should Geralt uncover his true identity, the Concerned Citizen reveals himself to be a Higher Vampire, meaning that he is such a zealot that he willingly supports a religion that wants to completely wipe out him and all non-humans.