Knucker is a dialect word for a sort of water dragon, living in knuckerholes in Sussex, England.
The knucker apparently caused a lot of trouble, consuming local livestock and even villagers, and so it was decided to slay the monster.
One version has the dragon slain by a knight-errant after the king of Sussex offered his daughter's hand in marriage to whoever rid them of the beast.
It was believed that knuckers could be found at knuckerholes in various places in Sussex, including Binsted, Lyminster, Lancing, Shoreham and Worthing.
However, even though the knucker hole in Lyminster is only thirty feet (9 m) deep, a local legend says that the villagers tied together the six bellropes from the church tower and lowered them into the pool, but they could not reach the bottom.