Lock, Shock, and Barrel are the three troublemakers of Halloween Town, always pulling off pranks to the Halloween Town's residents, and serving under the malevolent sack of bugs, Oogie Boogie. They are the secondary villains of the Tim Burton's stop-motion film The Nightmare Before Christmas.
Lock is the boy with the devil-themed clothing with a tail and devil mask face, acting as the leader of the team. Shock on the other hand is the female member, with a witch clothing and hat, and a mask with no facial expressions on it, serving as the team's reason and logic. And last but not least, Barrel is the short and dimwitted member of the trio with a skeletal clothing and mask. Together, they are extremely dangerous nuisances against minor threats like Santa Claus.
With the exception of Oogie Boogie, the trio seem to serve other powerful and terrifying villains like Maleficent, as seen in the video game installment, Kingdom Hearts II, or in most of the plotlines of the villains wars.