Eric II Valdemarsøn (c. 1290 – 12 March 1325) was Duke of Schleswig from 1312 until his death in 1325.
Already during the lifetime of Valdemar IV, he acted as his father's coruler and used the title of duke.
At the death of Valdemar IV in the spring of 1312, he immediately succeeded his father as Duke of Schleswig.
Shortly afterwards, he participated in the expedition of his feudal overlord, King Eric VI of Denmark, to Rostock.
However, part of the price Christopher had to pay to accede to the throne, was to accept the right of Duke Eric to the fief of Langeland.