Lugus is the name for the continental version of a Celtic god with a tendency to tricksterish behaviour, who was skilled at many things and identified with the Roman god Mercury. Records are slight and his footprint survives mainly in place names. He may have been a triple god actually made up of three other gods: Esus, Taranis and Toutatis. He was associated with ravens and roosters, mistletoe, horses, pairs of snakes, dogs and wolves, the tree of life, spears, shoes and bags of money.
The possible origins for his name include *leug “black”, *leuǵ “to break”, *leugʰ “to swear an oath”, and the very unlikely *leuk “to shine”. However, these have some bearing on later folk etymology in the Blessed Isles so they are worth bearing in mind.
Lugh has survived as the (eventual) high king of the Tuatha de Danaan – and later the Fair Folk – due to his prowess with spear and sling as well as being many-skilled. He had many epithets including Lámhfhada (“long arm” or “long hand”), Ildánach (“skilled in many arts”), and Samhildánach (“Equally skilled in many arts”). In terms of the Celtic Interpretation of mythology, there are a number of characteristics that the Irish version of Lugus took from the Otherworld that were clearly not part of the continental original.
In Irish tradition, he was the child of both the Tuatha de Danaan and the Formorians following a dynastic union leading to a political alliance, which places him in a more muddied, Otherworld-related position. Lugh went on to be fostered by Manannán mac Lir at Emain Ablach, drawing him further outside of the continental traditions. Manannán’s gifts to Lugh included means of transport over land and sea (or between our reality and the Otherworld).
Lugh is quite often listed as an ancestor of clans and great heroes, which is not unusual for any god, Otherworld-related or otherwise. However, there is some confusion as to whether these descents should actually be termed from Lugh-as-Lugus or from Lugh in the sense of an Otherworld origin. This is due to the name also being the traditional Gaelic word for the lynx (extinct in our reality since the end of the Roman Era). Oddly enough, the word lynx definitely derives from *leuk, probably due to the way cats’ eyes reflect light.
Lleu Llaw Gyffes is a hero of Welsh tradition. He was skilled with spears and stones (usually thrown rather than slung) with his epithet meaning something like “skillful hand”, but could also perform magics such as shapeshifting and craft shoes.
The Welsh Lleu is firmly a descendant of Dôn (the equivalent of the Tuatha de Danaan) through his mother, Arianrhod, and in the tradition’s earliest forms it is implied that his father was Arianrhod’s brother, Gwydion, who went on to foster and raise the child. However, Lleu had a twin brother who became a sea spirit, which echoes the influence of Manannán on his Irish equivalent, and the Welsh traditions firmly place the House of Dôn in the Gwynedd region of Wales, which gives them a strongly localised feel.
Although Lleu appears to have accreted less of the Otherworld influence than Lugh, the connection with the lynx remains. The traditional Welsh for lynx is llew, and Lleu’s name is often misspelled (along with associated slight shift in pronunciation) as Llew. However, there is no tradition of people claiming Lleu/Llew as an ancestor.