Juan Muerto is a pirate and a pig who battled with the 5th Phantom and Juliet Adams Walker various times. The first was before they were married and again several years later which almost saw the end of the 5th and Juliet's life.
Juan is a leader of men through fear and intimidation. He is handy with a whip and its his main choice of weapon.
In his final battle he fought against the 5th Phantom he managed to capture him through luck and after weeks of torture he unmasked the Phantom. The whole boat load of pirates died being blown up after Juan was stabbed and killed by Juliet.