Vicelinus was a 12th-century German bishop who served as the Bishop of Oldenburg. Born in Hamelin around 1086, he was raised by his uncle after being orphaned. He pursued extensive education, eventually serving as a teacher in Bremen and potentially studying under Abelard in Laon. Dedicated to missionary work among the Polabian Slavs, he established various religious foundations and was eventually appointed to lead the diocese of Starigard. He died in Neumünster in 1154 following a period of illness.