Wollert Otto Hallvard Konow Keilhau (1894 – 1958) was a Norwegian librarian and encyclopedist. He edited the encyclopedia Norsk konversasjonsleksikon Kringla Heimsins, published in six volumes from 1931 to 1934. He was also a co-editor of the second edition of the encyclopedia, issued from 1948 to 1954.[1]