Laurentius Christophori Hornaeus (1645 – April 27, 1719), also known as Lars Christophri Hornæus, was a priest of the Church of Sweden and witch-hunter in Torsåker and Ytterlännäs, Sweden.
He was born as Lars Christoffersson in Härnösand in 1645. During the 17th century in Sweden, the Latinized form of peoples names were common and their birthplace was sometimes added as a family name. Hornaeus most likely is the Latinized version of Härnösand. Lars started his theological studies in the 1660s and in 1667 he and his brother Petrus were both studying together at the University of Uppsala. Lars was ordained in 1672 and was then employed as an assistant or curate, to the "assistant minister" Olaus Erici Rufinius (1637-1672) in Ytterlännäs. Ytterlännäs is the parish for the city of Torsåker. He was also responsible for the annex parish in the Dal Hundred. Olaus Rufinius died in 1672, and Lars was appointed as the new "assistant minister" of Ytterlännäs.
In 1675 Laurentius Christophri Hornaeus engaged in the Torsåker witch trials which became the largest witch-hunt in Sweden's history.
It was a traditional that when a minister died, the clergyman who replaced him would marry his widow, or his daughter, depending on their age. This was termed "preserve the minister’s widow" (konservera prästänkan). Olaus Rufinius was already a widower when he died, and he had an unmarried daughter named Brita Olofsdotter Rufinia (1651-1730). Lars married Brita, and the wedding took place in the parsonage in Sunnanåker, in Ytterlännäs parish. Lars and Brita had a child: Lars Hornaeus (1682-1751) a minister, who would marry Elisabeth Wattrangia (1682-1743). Lars and Elizabeth would have a son: Jöns Hornaeus (1715-1778), a minister who documented the witch trials of his grandfather. Jöns would later marry Catharina Pihlwall (1727-1771).