Mettaton EX is a massive and dazzling figure in the Underground, standing at around 100 feet tall. He is most famous as a TV host, idol, and performer who lives and breathes for attention, ratings, and applause. He spends most of his time around Hotland, MTT Resort, and the CORE, where his shows are produced and broadcast across the Underground.

Mettaton EX has a sleek, humanoid figure with a stylish, futuristic design. His "skin" is smooth and pale, almost porcelain-like. He uses TV slang.