rex

the title given to a male monarch or ruler, especially in historical contexts

rey

• the Rex of somewhere

Collocations rex of Rome

• He was the first Roman rex.

  Él fue el primer rey de Roma.

a male lion, especially in heraldry or literature

león (macho)

• the Rex of somewhere

Collocations Rex of the jungle

• The lion is often called the king of beasts, or the rex.

  A menudo se llama al león el rey de las bestias o el rey.