An Imperial Eagle beaker (German: Reichsadlerhumpen), or eagle glass, was a popular drinking vessel from the 16th until the late 18th century in the Holy Roman Empire. The enamelled glass was decorated with a double-headed eagle, usually in the shape of a Quaternion Eagle. The Reichsadler means "Imperial Eagle" or double-headed eagle which was the emblem of the empire, while "humpen" refers to a cylindrical drinking glass. These beakers became the essential medium to represent the most popular explanatory model for the emergence of the Empire: the quaternion theory as represented by Hans Burgkmair.
The Imperial Eagle beakers showed the solidarity between the owner and the Empire and were very popular because of their decorativeness and luminous colors. But these drinking vessels were also valued for their generous size. Equally popular were the electors' beakers, which were decorated with illustrations of the emperor and electors as the most important representatives of the Empire.