Isaacus Rothovius (1 November 1572 – 10 February 1652) was a Swedish cleric known for his influential role as the Bishop of Turku in Finland from 1627 to 1652.

Born in Småland, Sweden, he was the son of a farmer named Börje Larsson and had a twin brother, Jonas Rothovius, who later served as the Superintendent of Kalmar.

Rothovius pursued an educational journey that led him to Uppsala, where he became a teacher to the Oxenstierna brothers and traveled to Germany for further studies.

Notable accomplishments include his involvement in expediting the translation of the Bible into Finnish, completed in 1642, and his role in educational reform.

Bishop Rothovius forced the Finnish Evangelical Lutheran Church and its priests to change several of their customs, such as reading different Bible passages from different sides of the church, and wearing colourful garments, which reminded him of Finland's Roman Catholic past.