King Midas is the leader of the Gold Brickers villain group.
King Midas' skin looks gold because he paints it that way thinking that it makes him look tough. His skin is very tough, however and Dr. Shelly Percey describes it as being "harder than a diamond".
According to the Lore AMA, King Midas "had the power to turn anything he touched into “gold” (which only looked like gold, had none of the properties, and was obviously fake). Since he was constantly tempted by what would appear to be wealth, but wasn’t, he became a criminal to steal REAL gold."