Mr. Lizard is a lizard. Not an ordinary one, but Mr. Lizard is a minion of the Yo Gabba Gabba.
Just like the group, he tortures you with his songs. That's why he's a horrible singer. He used to be a good singer, but he decided to get vocal lessons from Hatsune Miku (who can't sing for the life of this guy) which basically caused him to ruin his voice. When the Yo Gabba Gabba guys found Mr. Lizard, they fell in love with his awful voice and instantly made him their minion. And he's evil, of course.
Really evil. He's also a satanist, but Googolplex wouldn't let him join the Satanist Empire at first because of his horrible singing voice. But then Googolplex gained interest in Yo Gabba Gabba and Mr. Lizard, so he let them join.
He mostly hangs out with Muno, of course.
He used to hate Pencil, but now, he likes her.
He is also in love with Ms. Fox.
His singing might be bad, but WaMr. Lizard's is worse.