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.
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.