Wollert Otto Hallvard Konow Keilhau (8 February 1894 – 19 October 1958) was a Norwegian librarian and encyclopedist.

He was born in Kristiania as a son of Carl Keilhau (1864–1900) and Modesta Konow (1864–1931).

[3] In 1918 he married farmer's daughter Anna Mathilde "Magnhild" Østvold.

[4] He finished his secondary education in 1912, and enrolled in philology studies at the Royal Frederick University.

[1] He edited the encyclopedia Norsk konversasjonsleksikon Kringla Heimsins, published in six volumes from 1931 to 1934.