Eudaf Hen
He is remembered as a King of the Britons and the father of Elen Luyddog and Conan Meriadoc in sources such as the Welsh prose tale "The Dream of Macsen Wledig" and Geoffrey of Monmouth's Latin chronicle "Historia Regum Britanniae" . 
<triplet> Elen Luyddog <subj> Conan Meriadoc <obj> sibling <triplet> Conan Meriadoc <subj> Elen Luyddog <obj> sibling <subj> Historia Regum Britanniae <obj> present in work <triplet> Geoffrey of Monmouth <subj> Latin <obj> writing language <subj> Historia Regum Britanniae <obj> notable work <triplet> Historia Regum Britanniae <subj> Geoffrey of Monmouth <obj> author