Werner of Eppstein (c. 1225 - 2 April 1284) was the Archbishop of Mainz from 1259 until 1284.

Werner was a son of Count Gerard II of Eppstein, and in childhood his parents decided he was to have a church life. He was educated in Mainz and worked as a clergyman. As two members of his family were archbishops of Mainz (Siegfried II and Siegfried III), Werner quickly rose through the ranks of the church. He became the provost of Mariagreden in 1248, the provost of St Peter in 1249, and the provost of St Peter and Alexander in 1257. The last two carried an archdeaconate, making Werner powerful in the archdiocese.

In October 1259 Werner was elected the Archbishop of Mainz. In 1261 Werner crowned Ottokar II of Bohemia after much dispute. Werner like his predecessor also attempted to increase the secular territory of the archbishopric in Hesse and Thuringia and placed those lands under interdict, but as it threatened the territories he already had he signed a peace treaty with them in 1263. In the Imperial elections Werner attempted to end the interregnum through crowning the last Hohenstaufen, the minor Conradin, but these efforts failed due to the papacies anti-Hohenstaufen policies. After Conradin was killed in 1268, he espoused the cause of Richard of Cornwall.

After Richard died in 1272, Werner at the Imperial election chose Rudolph I of Habsburg. Werner accompanied Rudolph on campaign in 1273 against Ottokar II. Ottokar attempted to separate the Bishoprics of Prague and Olomouc from Mainz, and to grant to the Bishop of Prague the right to crown the Kings of Bohemia. In 1275 Werner again attempted to increase the territory of the archbishopric, which led to new tensions between him and the cities of Mainz and Erfurt. Werner died in Aschaffenburg in 1284 and was buried in Mainz Cathedral. He left the archbishopric in a strong position with many enemies.

Preceded by:

Werner of Eppstein

Succeeded by:

Gerard I of Dhaun Archbishop of Mainz
1259 - 1284
Henry II