Waiwatt

His name is Waiwatt.
Like "why" and "what"
But it's actually "wai" likeawaifu//shot
And "watt" like electric watts. 
It's a play on words.
Because he's made to answer questions.
Saying his name sounds like you're asking a question.
And when you call his name, he'll answer you.

He's a robot made by a genius teenager to help him study for tests, until the teen started using him to cheat. When he finally got in trouble for it, he threw the failed creation away where no one could find it. In Undertale, it was the hole to the Underground. Pretty much everything new fascinates him, since he was programmed to learn things in order to answer more questions for his creator. He generally takes everything seriously, but also has a sweet and caring side.

*Yes, that is the actual shape of his head, it's not just melo's anime style bleeding.

*He does not have real hair unless it's the HAO/Human version. The 'hair' is actually a white plastic part of the head that is the top and back. It has been cut out and shaped to resemble a hairstyle, but it is a solid plastic piece. 

*His limbs are attached by floating magnets. He is made of 100% recycleable meterial, mainly aluminum and plastic. He cannot hover above water.