Dreifaltigkeitskirche, Lutheran church in Osternburg district, Oldenburg, Germany.

The Dreifaltigkeitskirche is a single-nave brick church built 1614–1616 and donated by Count Anton Günther. A sandstone tablet with the founder's coat of arms sits above the south entrance. In 1734 the building was extended westward by one window bay and a tower, whose copper roof dates from 1927. Inside, a painted baroque beam ceiling of 1634 and a carved, painted gallery of 1636 survive, along with a sandstone pulpit bearing the countly couple's arms.

Built between 1614 and 1616 and donated by Count Anton Günther, the church was enlarged in 1734 by one window bay and a tower to the west. A four-line stone tablet set into the tower wall beneath the sound window reads "Gott sey uns gnädig und segne uns. Ps. 67. Anno 1734". The tower received a new copper roof in 1927.

The name refers to the Trinity; the larger bell carries a Latin inscription and is called Trinitatisglocke. Names and years of service of the pastors from 1616 to 1978 are recorded beneath the pulpit. The churchyard surrounding the building, the Alte Osternburger Friedhof, once held the parsonage and the school.

The church stands within the Alter Osternburger Friedhof, the old cemetery that surrounds it; a grave vault on the south side dates to 1710, and a separate soldiers' cemetery occupies the northwest corner. The organ gallery is reached by an outside staircase. The two bells hang in the bell chamber of the west tower added in 1734.

The larger bell, cast in August 1650 by the Lorraine founders Claudius Voillo and Gottfried Baulard, is called Trinitatisglocke after its Latin inscription; it measures 95 cm across and weighs about 520 kg. The smaller one, 82 cm and 330 kg, hung in Kieslingswalde in Silesia from 1474, was spared from melting down in the Second World War and reached Osternburg in 1951.