Lock is six years old and supposedly the leader of Oogie's Boys, but does not think thoroughly and actually appears to be the least intelligent of the three. Lock wears a devil costume; his barbed tail moves as though alive, his teeth are pointed sharply, his face is narrow and long-jawed, and his hair is waxed into two horns making him, literally, a handsome devil. He loves being large and in charge, and gets upset when others insult him or take the lead. However, he goes along with others' ideas if he cannot come up with anything himself. Without his mask he might not have horns but his handle bar style hair makes it look really close.
Lock is dressed as a devil, wearing a plain, long-sleeved, tattered red shirt, and pants of the same color. His brown shoes have pointed toes that curl upward, and he seems to wear pale orange gloves. His skin is an unhealthy grey color, his eyes are an eerie yellow and his lips are sky blue. His upper eyelids are a pink color, while the lower one is periwinkle. His chin is rather large and the top of his head is quite flat. His ears are set rather low on his head, and his eyebrows are the same shade of red as his clothes, while the rest of his hair is a darker red-brown color. He styles his hair in such a way that he has two "horns" in the front. His nose is pointed, but not nearly as large as Shock's. His mask is a faded red devil's face with horns that curve upward much more than Lock's hair. The mask's mouth is curled into a ghastly smile, showng sharp teeth. Lock's outfit is completed by a red, pointed tail, though it is unclear whether or not this is an accessory.