Grim Reapers are in charge of deciding whether a dying soul should be allowed to continue living or to die with scythes that resemble gardening tools (some of which shouldn't even exist in that timeline such as a lawn mower and a chainsaw). They must remain neutral and must not kill for enjoyment. In the manga, there are three Grim Reapers introduced so far: Grell Sutcliff, William T. Spears and Ronald Knox (ロナルド・ノックス,). Grell forges a partnership with Madame Red after witnessing her murder a former patient and helps her murder prostitutes. The two become known as Jack the Ripper. When they are exposed as the killers, William T. Spears comes to the human world to punish Grell. Spears belongs to the Dispatch Management Division. Grell's scythe is confiscated and Grell does not reappear in the manga. Ronald Knox is portrayed as easy-going and social and uses a scythe in the shape of a lawn-mower. In the anime adaption, Undertaker is a legendary Grim Reaper in the Management level. He is highly respected by Spears. Although he is retired, Undertaker can access the Grim Reaper Library and alter the books. In the last episode of the anime adaption, the Grim Reapers cut away tainted souls unfit to be kept in the Grim Reaper Library. So far all Grim Reapers introduced have been shown to wear eyeglasses at some point in their life.
Grell, in the anime adaptation, is a flamboyant Grim Reaper who works as Madame Red's butler. He is initially portrayed as worthless and is often seen in the anime adaption trying to commit suicide after mishandling tasks, something he did so often the Phantomhive staff just gave up on trying to stop him. As a Grim Reaper, he is characterized with red hair and shark-like teeth. Grell often refers to himself as a female and verbalizes his infatuation with Sebastian, much to the latter's disgust. He meets Madam Red while she is murdering a former patient. Grell and Madam forge a partnership and continue the murders. They are known as "Jack the Ripper". Grell's Grim Reaper scythe is illegally modified to look and function like a chainsaw. When cutting someone with his Scythe, their past memories are played out like a video reel; this is referred to as "Cinematic Record". Sebastian almost kills Grell with the Grim Reaper's own scythe, but he is stopped by William Spears. William beats Grell and takes him back to headquarters. In the manga, Grell has not appeared since. However, he makes a reappearance in the anime adaption, where his role is lengthened through missions William assigns him to investigate. His scythe is confiscated and Grell has to rely on small scissors able to cut through anything. At the anime's conclusion, William returns his chainsaw scythe so that he can help the other Grim Reapers destroy the tainted souls caused by Angela and Ash.
Grell Sutcliffe (グレル・サトクリフ)