Wikipedia
Marțolea is a Demonic entity in Romanian mythology (especially in the regions of Bukovina and Maramureș). The entity's gender is unclear, as it can shapeshift at will. It lives up in the mountains and descends on Tuesday nights to lure with its singing and punish the women caught working.
Called also Marț Sara (the old Romanian words for " Tuesday Evening") is a malefic entity, who demands the semi-holy day of Tuesday to be respected and who forbids four women's chores: spinning of the wool, sowing, boiling laundry and baking bread. This is a pagan being.
Marțolea's punishments for these things are harsh like: killing by ripping, hanging the guts on nails to the wall and around the dishes, in the unmarried women cases. For the married women the punishments are killing or possessing their baby or their husband who is far from home.
Usually his form is of a goat with human like head, horns & hooves. He can shape shift into a big old woman dressed all in black, ugly, soldier/warrior or as a handsome man. To married women it shows as an old woman, to married men as a virgin and to unmarried women as a young charming man.
In some regions, there is a different character called Joimârița, another form of the Romanian word for Thursday this one however punishes lazy children.
Marțolea repays the women who keep the Tuesday day sacred by leaving them eggs on their doorstep or flowers from the highest mountains in Bukovina. On the first night of March, women that wear March Trinkets (Mărțișor) are repaid by Marțolea with a silver coin that the girls will have to keep all year.