A jack-o'-lantern is a carved pumpkin associated with the holiday Halloween. To make one, the top is cut off and the insides scooped out. A face or picture is carved into the side, a lit candle is placed inside, and the top replaced. The light then flickers giving an eerie effect.
Even though a villain with name and abilities based on the Jack-O'-Lantern exists in the Marvel Universe, he has never appeared in the Animated Universe.