Saint Rimbert (or Rembert) (c. 830 - 11 June 888 in Bremen) was archbishop of Hamburg-Bremen, in the northern part of the Kingdom of East Frankia from 865 until his death in 888. He most famously wrote the life of Saint Ansgar, the Vita Ansgari, one of the most popular hagiographies of the middle ages. Biography. Little is directly known about Rimbert, much of the information available regarding his life comes from the Vita Rimberti, a hagiography written by an unknown author, likely produced some time in the 10th century.
https://en.wikipedia.org/wiki/Rimbert