X! Gaster

XGaster is the main character of XTale and Underverse. He is the sole creator of the XTale universe.
XGaster is a more enigmatic character, keeping aloof from the main characters except in special circumstances, such as when XTale!Sans attempts to kill XTale!Frisk on stage. He is also highly intelligent: knowing everyone would soon turn against him, he took his soul and gave it to Ink for safekeeping. Despite this, he displays sociopathic and abusive tendencies towards his children, viewing them more as "experiments" than anything else. He cares little for others' feelings, only wanting them to fall into his hands and using them for his own ends, like a puppet. He is also shown to be extremely control-obsessed and exhibits some narcissistic traits, such as scolding his children for resisting and accusing them of being "ungrateful." He also refers to universes other than his own as "garbage." All of this shows that beneath his stoic and calculating demeanor lies a childlike figure who views his universe as a toy box. In XTale IX, he seems to briefly resurface his softer side after a conversation with Papyrus. He says that not having power over the world has given him a new perspective, then mentions that he "hated it," says he's come too far to stop, and returns to his former self.
In XTale IX, he seems to briefly resurface his softer side after a conversation with Papyrus. He says that, without power over the world, he saw it in a new light, then mentions that he "hated it," saying he'd gone too far to stop and returning to his old self. The animated prequels reveal that he was once a genuinely kind person who simply wanted to create a perfect world for his children. However, over time, he lost all those qualities he once had and became more cruel as he grew increasingly desperate.