[6] The programme is set in Aberystwyth, Ceredigion, Wales, and the three series were filmed in and around the town, often in rural locations.

Wales Arts Review wrote: "Y Gwyll has been shot with real intelligence; simple, subtle and with both eyes focused on the feeding of the atmospheric cloud over the piece.

[4] On a tight budget, funds that took two and a half years to raise, the total production cost was £4.2 million.

[12] The programme-makers received £215,000 in repayable business funding from the Welsh Government, and the first series was mainly filmed in Aberystwyth and the surrounding county of Ceredigion on the west coast of Wales, over a 124‑day period in 2013.

[15] Danmarks Radio (DR), acquired the rights in 2012 to broadcast the show in Denmark,[16] before filming had commenced.