Stoatly Grimes -
Alfirin - In the books Sauron had neither the "Giant warrior" nor "the Eye" forms.
At first, back in the Second Age, he had been a shape-shifter, able to assume any guise from a wolf to a snake to Elven-like fair Annatar.
Then when his material body had perished in the fall of Numenor, he lost the ability to assume a fair guise. He made himself a new body - humanoid, higher than any man "but NOT gigantic". This shape was terrible to look upon.
Then Elendil and Gil-Galad brought Sauron down and Isildur took the Ring. In a millennium or more, Sauron was able to make himself a new body yet again - seemingly the exact copy of his last one, with the missing finger. In this guise he stayed till the very end.