Oh, bother. Well, have it your way. I'll just skip to the part where I kill you all!
Gigameth, also known as Gigames, is the evil advisor to King Gorn of Saronia in Final Fantasy III. He took control of the King's mind with a magic spell and forced the soldiers of Saronia to engage in civil war. He then had the King exile Prince Alus when he protested the war.
When Alus returns with the main party, Gigameth tries to have the King kill his own son. However, the King refuses, claiming that he would rather die than hurt his child and fatally stabs himself, ending Gigameth's spell. Gigameth then transforms into the monster Garuda and attacks the party, but dies at the battle's end.
Gigameth is fought at Saronia Castle as a boss after he reveals his true form, Garuda.