This thesis reaffirms the Celtic influence on Beowulf. The first chapter reevaluates past attempts to demonstrate a Celtic connection with particular emphasis on the work of Martin Puhvel and R. Mark Scowcroft. The second chapter compares Grendel’s Mother to the Lady of the Lake, from the Prose Lancelot, using the Celtic water hag motif. The third chapter analyzes how Grendel exemplifies the Celtic motifs of the violent child and the wild man by comparing him with Cu Chulainn, from the Táin Bó Cúailnge, Lancelot, from the Prose Lancelot, and the Celtic wild man tales surrounding Suibhne, Myrddin, and Lailoken. The final chapter uses Michael D. C. Drout’s Lexomic analysis and a network analysis by Pádraig Mac Carron and Ralph Kenna to problematize the assumed unity of the text. Therefore, this thesis provides both narrative and textual evidence to validate the Celtic influence on Beowulf.