Greek cross
The Greek cross is a type of Christian cross that is used especially by Eastern Orthodoxy and Early Christianity. It is also known as the crux immissa quadrata. It has all arms of equal length. Often the arms curve wider as they go out.
Greek Cross Media
7th-century Byzantine solidus, showing Leontius holding a globus cruciger, with a stepped cross on the obverse side
Double-barred cross symbol as used in a 9th-century Byzantine seal