LLYWARCH ap BRAN (fl. c. 1137), 'sylfaen-ydd' un o 'Bymtheg Llwyth Gwynedd.' Dywedir ei fod yn frawd-yng-nghyfraith i Owain Gwynedd-merched i Gronw ab Owain ab Edwin, arglwydd Tegeingl, oedd gwragedd Llywarch ac Owain Gwynedd. Dywedir hefyd iddo, fel Hwfa ap Cynddelw, wasnaethu Owain Gwynedd fel stiward, ei fod yn byw yn nhref-gordd Tref Llywarch, Mon; fe'i disgrifir hefyd yn arglwydd cwmwd Menai. Am enwau rhai teuluoedd yr oedd eu haelodau yn hawlio bod yn ddisgynyddion Llywarch gw. Philip Yorke, Royal Tribes (arg. 1887), 177-80. Philip Yorke, Royal Tribes of Wales (arg. 1887); T. Pennant, Tours {arg. 1883). W.LL.D. Llywarch ap Bran (fl c 1137), founder of one of the 'Fifteen (Noble) Tribes of Gwynedd,' is described as brother-in-law of Owain Gwynedd, their wives being daughters of Gronw ab Owain ab Edwin, lord of Tegeingl. Like Hwfa ap Cynddelw, he is said to have been steward to Owain Gwynedd and to have lived in the township of Tref Llywarch, Anglesey; he is also described as lord of the commote of Menai, Anglesey. For the names of some of the families who claimed descent from him see Philip Yorke, Royal Tribes of Cymru (1887 ed), 177-180. [Dictionary of Welsh Biography p596]