Quaternion Eagle

The Quaternion Eagle (German: Quaternionenadler; Italian: aquila quaternione), also known as the Imperial Quaternion Eagle (German: Quaternionen-Reichsadler) or simply Imperial Eagle (German: Reichsadler), was an informal coat of arms of the Holy Roman Empire.

Introduced around 1510 by Hans Burgkmair, the Quaternion Eagle mixed two pre-existing concepts: the Imperial Quaternions and the Imperial Eagle (double-headed eagle).