Gwyllgi or wolf hound is one of the Welsh Shucks. The Gwyligi or Gwyllgi is a Black Dog of Wales that stalks travellers scaring them and sometimes attacking them. Its name means ‘the Dog of Darkness’ or ‘Dog of Twilight’ the Gwyligi had fiery eyes and could be heard howling in the night. Whoever encountered the Gwyllgi and caught sight of its fiery gaze would be instantly paralysed. Some say that even its howl had the power to paralyse people with fear. It would trot alongside lonely travellers at night, stalking them slowly and silently before pouncing and attacking them.
The Gwyllgi was first mentioned in a rare book called ‘The Vale of Glamorgan’ in 1839 and there have also been reports of the Gwyllgi seen at Anglesey in Wales. Like other Black Dogs of Wales the Gwyllgi looked like a mastiff, very large, black in colour with a shaggy pelt.His description of this creature, seen on a lane leading into the Wrexham village, echoes those of the Gwyllgi, the mysterious dog-like apparitions of Welsh folklore. These commonly reported yet inexplicable spectres have their counterparts in England, where they go by a variety of regional names, including Padfoot, Skriker, Trash and Black Shuck. In the literature, they are usually simply referred to as Black Dogs.