Sloth

Sloth is the fifth Homunculus created by Father. Appearing as a giant, muscular, but mentally slow man, Sloth spends most of the story digging the country spanning underground tunnels that make up the Father's mysterious transmutation circle. A conversation between Greed and Lust implies that Sloth have dug tunnels for at least a hundred years. Not surprisingly, he seems eager to finish his work so he can rest at last.