Johan Ernst Welhaven Sars (11 October 1835 – 27 January 1917) was a Norwegian historian, publicist and editor. His main work was
Udsigt over den norske Historie, four volumes issued from 1873 to 1891. He co-edited the magazines
Nyt norsk Tidskrift (with
Jens Lieblein) from 1877 to 1878, and
Nyt Tidsskrift (with
Olaf Skavlan) from 1882 to 1887. He was politically active for the
Liberal Party of Norway, and among the party's most central theoreticians.