Sawyl Penuchel or Ben Uchel ("high-head", "arrogant"), also known as Samuil Penisel ("low-head", "humble"), was a British king of the sub-Roman period, who appears in old Welsh genealogies and the Welsh Triads.
The genealogies, in which he appears under both epithets, make him the son of Pabo Post Prydain, a descendant of Coel Hen, the presumed king of the Old North. John Morris locates Sawyl in the south Pennines area (the modern Peak District, a name which may date from its settlement by the Anglian Pecset). He is listed as one of the "Three Arrogant Men of the Island of Britain" in the Welsh Triads.
Other genealogies say he was the father of St. Asaph. Elis Gruffydd's Chronicle says that his daughter married Maelgwn Gwynedd. An Irish genealogy says that a "Samuel Chendisel" married Deichter, daughter of Muiredach Muinderg, the king of Ulster, and they had two sons: Sanctan, who became bishop of Cil-dá-les and founded Kilnasantan in County Dublin, and Matóc Ailithir. The Irish Liber Hymnorum confirms that both Sanctan and Matóc came to Ireland from Britain.
According to the Welsh Life of Saint Cadoc, a king named Sawyl Penuchel held court at Allt Cunedda near Kidwelly in Carmarthenshire. Cadoc pursued Sawyl's warband after they stole food from Llancarfan Abbey. He found them sleeping under a tree and cut off their hair, before fleeing to a nearby bog. When Sawyl and his men gave chase, they all drowned in the bog. Whether this is the same king, having fled to Wales after his northern kingdom was overrun by the Saxons, a different man of the same name, or simply an error by the composer of the Life, is unclear. This Sawyl was supposedly buried in a nearby mound known as Banc Benuchel.