Osbert de Bayeux (floruit 1121 to 1184) was a medieval English cleric and archdeacon in the Diocese of York. A relative of Thurstan, the Archbishop of York, Osbert probably owed his ecclesiastical positions to this relative. After Thurstan's death, Osbert was opposed to one of the candidates for the archbishopric, William fitzHerbert, and worked to secure fitzHerbert's deposition and replacement by Henry Murdac. After Murdac's death in 1153, Osbert tried to prevent the return of fitzHerbert, but these attempts were unsuccessful. When fitzHerbert died suddenly in 1154, Osbert was accused of murdering the newly returned archbishop. Although he was never convicted of the murder in either a secular or an ecclesiastical court, he was stripped of his clerical status and became a layman before 11