Lars Olsen Skrefsrud (4 February 1840 – 11 December 1910) was a Norwegian missionary and language researcher in India. Together with Hans Peter Børresen he is regarded as the founder of the Norwegian missionary organization Santalmisjonen (from 2001 a part of Normisjon). He was followed by the missionary, linguist and folklorist Paul Olaf Bodding. He studied at the missionary school of Johannes Evangelista Goßner in Berlin, where he was prepared for his mission.
Skrefsrud came from the small place of Fåberg north of Lillehammer in Norway. As a young man he was imprisoned for three years, and during his incarceration he became a Christian and started to study both the Bible and languages, and became one of Norway's foremost linguists.