In another story the warshaw Basilisk is killed but I don't remember who did it.
Basilisk
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The Obra Water Monster
Loch Ness is not the only lake with a reputation for a Monster. The River Obra, a small offshoot of the River Warta, in the west of what is now Poland, is said to be the home of a similar giant water-based 'monster'.
The Obra Water Monster
Rusalka - Polish / Slavic Tree Spirit
In traditional Pre-Christian folklore the Rusalka or Rusalki, was seen as the most dangerous ghost of all. Polish legends says that Rusalka spirits who girls or women who died an unnatural or violent death. This succubus type spirit seeks to continue to exist by drawing the energy of life from all nearby living things. A nasty and attractive tree-dwelling Polish fairy (faerie)! Like other female nature spirits Rusalka's power comes from her powerful sexual attraction. Rusalka's erotic appearance and sweet song is said to be enough to lure any red-blooded male into the forests and lakes where they would have their spirit sucked from them and die. Although as Rusalka nymphs are said to be affectionate lovers, their victims die happy!
Rusalka - Polish / Slavic Tree Spirit