Penceilogi is a small village on the northern outskirts of Llanelli, Carmarthenshire, Wales. It is bordered by Bryn to the east, Dafen to the north-west, Pemberton to the west and Cwmcarnhywel to the south. Administratively it lies within the community of Llanelli Rural and occupies the spur between the Dafen and Cwm Carnhywel valleys, its streets stepping up from about 40 m to 90 m above sea level on the flanks of Bryn hill. The built-up area merges westwards into Pemberton and eastwards into Bryn, while minor lanes give south-facing views towards the Burry Inlet. Llanelli Rural as a whole recorded 23,058 residents at the 2021 census, making it the most populous rural community in Wales and the largest population cluster outside the town's historic borough limits.