Eldena Abbey (German: Kloster Eldena), originally Hilda Abbey (German: Kloster Hilda) is a former Cistercian monastery near the present town of Greifswald in Mecklenburg-Vorpommern, Germany. Only ruins survive, which are well known as a frequent subject of Caspar David Friedrich's paintings, including the famous Abtei im Eichwald ("Abbey in the Oak Forest").

In the 12th century the Baltic coast south of the island of Rügen belonged to the Rani principality of Rügen, which in its turn was subject to the Danes. The Danish Cistercian monastery, Esrum Abbey, was thus able to found a daughter house in the area, Dargun Abbey, at Dargun, west of Demmin, in 1172. When in 1198 this monastery was destroyed in fighting between Denmark and Brandenburg, Jaromar I, Prince of the Rani, whose wife was of the Danish royal house, offered to re-settle the monks at a new site at the mouth of the River Ryck, close to the boundary between the territory of the Princes of Rügen, and the County of Gützkow, since the early 1120s subordinate to the Duchy of Pomerania.

The offer of the site, which included profitable salt pans,was accepted, and in 1199 Hilda Abbey, now Eldena Abbey, was founded, and confirmed by Pope Innocent III in 1204.

The monastery became wealthy from the salt trade and was very influential in the Christianisation of Western Pomerania.

It also brought about the foundation at the beginning of the 13th century of the town of Greifswald, which started out as the monastery's trading settlement opposite the salt pans, near the point where the via regia, an important trade route, crossed the river.

The east end of the abbey church was built in about 1200, while the conventual buildings date from the mid-13th and 14th centuries, all in Brick Gothic. The final stages of construction were the west front and the nave of the church, which were completed in the 15th century.