I remember that a German symbol of World War II belonged to an eagle. What's the name of that symbol?

It is the only eagle. The full name of Nazi Germany in World War II was the Third Reich. Before that, the Second Empire was established by William the Great. The earliest predecessor was the Holy Roman Empire. The family emblem of ancient Rome was originally a female wolf, and later it was changed to the only eagle. After the establishment of the Eastern Roman Empire, it was changed to double eagle. Germany inherits the Roman tradition and takes the eagle as the national symbol.