St. Olav's Church (Norwegian: Olavskirken) are a ruins in the municipality of Bamble in Telemark, Norway.
The church ruins are located by the E18 which passes through Bamble. The ruins are situated northeast of the newer Bamble Church (Bamble kirke) which was completed during 1845. Bamble Church was constructed in part with stone from the ruins.
St. Olav's Church was built of stone before 1150 in Romanesque-Norman style inspired by English Norman architecture. It was dedicated to St. Olaf, patron saint of Norway and served as a center for the veneration of St. Olaf by the nearby Gimsøy Abbey. The church was probably about four feet longer than the ruins suggests. In that case, it would have been the largest stone church in Telemark during that period. It had a number of unusual building features, including a chancel screen (lektorium) and a separate room for earthly values. This small room, which today is called Maria's Chapel (Mariakapellet), was inspired by Bishop Halvor Bergan. Since 1998 it has been heated, lighted and open to the public all year round.
After Protestant Reformation, the church was re-named Skeidi Church (Skeidis kirkja i Bamblum). Until 1738 the parish comprised Sannidal, Skåtøy, Kragerø and Bamble. Probably the church was the main church within the district of Grenland and therefore had the highest status of all churches in the area.