; "Man Dog Rough Grey" is a murderous monster

Monster

A monster is any fictional creature, usually found in legends or horror fiction, that is somewhat hideous and may produce physical harm or mental fear by either its appearance or its actions...

 in Welsh literature

Welsh literature

Welsh literature may be used to refer to any literature originating from Wales or by Welsh writers:*Welsh-language literature for literature in the Welsh language*Welsh literature in English for literature in the English language...

 and mythology

Welsh mythology

Welsh mythology, the remnants of the mythology of the pre-Christian Britons, has come down to us in much altered form in medieval Welsh manuscripts such as the Red Book of Hergest, the White Book of Rhydderch, the Book of Aneirin and the Book of Taliesin....

, sometimes identified as a werewolf

Werewolf

A werewolf, also known as a lycanthrope , is a mythological or folkloric human with the ability to shapeshift into a wolf or an anthropomorphic wolf-like creature, either purposely or after being placed under a curse...

. He made a corpse of a Briton

Britons (historical)

The Britons were the Celtic people culturally dominating Great Britain from the Iron Age through the Early Middle Ages. They spoke the Insular Celtic language known as British or Brythonic...

 every day, and two on Saturday so as not to have to kill on a Sunday. He was ultimately assassinated by the hero Diffydell mab Dysgyfdawd, which was recorded in the Welsh Triads

Welsh Triads

The Welsh Triads are a group of related texts in medieval manuscripts which preserve fragments of Welsh folklore, mythology and traditional history in groups of three. The triad is a rhetorical form whereby objects are grouped together in threes, with a heading indicating the point of likeness...

as one of the "Three Fortunate Assassinations". Garwlwyd also appears in the early Arthurian poem Pa Gwr yw y Porthwr, in which he is described as having fought in the Battle of Tryfrwyd against the Arthurian heroes Bedwyr

Bedivere

In Arthurian legend, Sir Bedivere is the Knight of the Round Table who returns Excalibur to the Lady of the Lake. He serves as King Arthur's marshal and is frequently associated with Sir Kay...

 and Manawydan

Manawydan

Manawydan fab Llŷr is a figure of Welsh mythology, the son of Llŷr and the brother of Brân the Blessed and Brânwen. The first element in his name is cognate with the stem of the name of the Irish sea god Manannán mac Lir, and likely originated from the same Celtic deity as Manannán...

.