Giygas

Giygas, also known as Giegue in, is the main antagonist in Mother and EarthBound.

Giygas was raised from infancy by a woman named Maria and her husband George, both of whom were abducted from Earth in 1906. During this time, George studied the aliens' PSI powers without their permission, culminating with his escape back to Earth.

In
In Mother, Giegue invades Earth, abducting parents and sending other aliens and robots to attack people, especially Ninten. His first attempt was to have Ninten's lamp assassinate him, but this failed attempt leads Ninten to start his journey, discovering who Giegue is, and what relation he had to his family.

Atop Mt. Itoi, Giegue is confronted by Ninten and his companions. Before the fight actually begins, Giegue seems to offer to spare Ninten's life out of respect for Ninten's great-grandparents who raised him, asking him to come with him back to his planet. Ninten declines, and after being turned down, Giegue attacks him, and is invulnerable to every attack.

After Ninten and his friends sing the Eight Melodies multiple times, Giegue is forced to retreat as the emotional stress becomes too much for him to handle, promising to return and attack again.

For clarity, the player cannot name a character Giegue.

In-game description
"(Ninten hears the voice of Queen Mary) Giegue cannot be defeated with force... You cannot defeat Giegue with a weapon of any kind. You must SING my lullaby, with all your feelings... SING my lullaby with all your heart."

In EarthBound
In EarthBound (the subtitle of which is "The War Against Giygas"), Giygas has ruled the world ten years into the future, and uses the Apple of Enlightenment to see further into the future. Giygas witnesses his defeat at the hands of Ness and his party, and sets out to prevent this from happening.

Ness hears about him from Buzz Buzz, who came from the future to warn him about Giygas' plot. Shortly afterwards, they are both attacked by one of Giygas' henchmen, a Starman Junior.

Ness goes through all of Eagleland to harness his powers in order to defeat Giygas, and gains three fated companions - Paula, Jeff, and Poo - along the way. Giygas must be fought in the past, and to go there, the Phase Distorter must be used. Because time travel is described as having the potential to destroy their bodies, the party must transfer their souls into mechanical bodies in the process. As they fight their way through the Cave of the Past, they approach what appears to be a giant machine composed of various metal tubes. When they reach the center, they find Pokey, who is turned blue by Giygas' corruption. Pokey reveals that Giygas has destroyed himself with his own power, and exists in a physical form only through the Devil's Machine. Pokey proceeds by "waking up" the alien leader, only for it to take the appearance of Ness' face in the machine. During the first phase of the battle, the Devil's Machine not only protects Giygas from harm, but rebounds attacks back at the user with double damage. Giygas also shows himself capable of using PSI Rockin, a move previously reserved for use by Ness. As a result, the player must focus his or her attacks on Pokey, and must avoid using moves such as PSI Rockin, which will damage Giygas and therefore rebound on the user.

When Pokey is damaged sufficiently, he begins taunting the protagonists, and turns off the Devil's Machine to unveil Giygas' true form, an eerie red mist in the shape of a screaming face. Pokey reveals that he himself is terrified by the alien's form, while warning that he is undefeatable. After dealing enough damage to Giygas, a scene will be triggered in which Pokey continues taunting them, telling them the only thing they can do is "beg for help". In the ensuing phases of the battle, Giygas will eventually heal any damage done to him, making him impossible to defeat by usual means. His main attack is reprised from the previous game, where he will make "inexplicable attacks" that randomly take the form of various PSI moves. The only way to defeat Giygas is by using Paula's "pray" ability. The party's prayers reach out to the people of Eagleland they meet, and as more people join in prayer for the heroes, Giygas begins taking increasing damage, each turn splitting his form and becoming more convoluted and distorted. The final "blow" is dealt by the player praying in support of the party, which deals devastating damage to Giygas, killing him and winning the battle.

Throughout the fight, Giygas talks to Ness before attacking, much like his pattern in the previous game towards Ninten. As opposed to his long speech in Mother, however, he makes very vague and simplistic statements such as "I feel good" and "It hurts".