Mavka
Mavka (, "mavka", , "navka", , "nyavka"; , "navi" (plural) – from ) is a type of female spirit in Ukrainian mythology. She is a long-haired figure, sometimes naked, who may be dangerous to young men. The spirits known by this term represented the souls of girls who had died unnatural tragic or premature deaths, particularly unchristened babies. Mavkas often appeared in the form of beautiful young girls who enticed and lured young men into the woods, where they "tickled" them to death. Mavkas had no reflection in water, did not cast shadows, and had "no back", meaning that their insides could be seen . (Those were more often called "Nyavka" and they were believed to live in Western Ukraine, which has more dangerous mountain rivers than Central Ukraine, while Mavkas, who were believed to live in Central Ukraine, had their backs.) In some accounts, they were also said to help farmers by looking after cattle and driving out wild animals. They were believed to live in groups in forests, mountain caves, or sheds, which they decorated with rugs. They made thread of stolen flax and wove thin transparent cloth for making clothes for themselves. They loved flowers, which they wore in their hair. In  the spring they planted flowers in the mountains, to which they enticed young men, whom they tickled to death. On Pentecost (known as Mavka's Easter, ) they held games, dances, and orgies. A demon accompanied them on a flute or pipes. To save a dead unchristened baby's soul, one had to throw up a kerchief during Pentecost holidays, say a name and add "I baptise you". A rescued soul would then go to heaven. If a soul lived up to seven years and did not go to heaven, a baby would turn into a mavka and would haunt people . It is believed that the first mavka (or rusalka) was Kostroma. According to the legend, siblings Kostroma and Kupalo once ran into a field to listen to songs of bird Sirin, but Sirin stole Kupalo and carried him into the Nav. Many years later, one day, Kostroma walked the shore of the river and made a wreath. She boasted that the wind would not blow the wreath off her head. According to the belief, that meant that she would not marry. This boast was not approved of by the gods. The wind became stronger and eventually blew the wreath from  Kostroma's head into the water, where it was later picked up by Kupalo, who was nearby in his boat. According to Slavic customs, the one who picks up the wreath must necessarily marry the girl who made it. Kupalo and Kostroma fell in love, and shortly after they were married, without any knowledge that they were brother and sister. After the wedding, the gods told them the truth. Because they could not be together, Kupalo and Kostroma committed suicide: Kupalo jumped into the fire and died, while Kostroma ran to the forest, threw herself into the forest lake and  drowned. But she did not die, she became a mermaid (mavka). Walking around that lake, she seduced the men she met on her path and dragged them into the water abyss. She mistook them for Kupalo, and found out that the caught young man was not her lover only when he had already drowned. Seeing this, the gods realised that their revenge was too cruel and repented. But to give Kupala and Kostroma a human body again was impossible, so instead they turned them into the flower with yellow and blue petals, in which the fiery-yellow color was the  color of Kupalo, and the blue one, like the waters of a forest lake, was the color of Kostroma. The Slavs gave the name Kupalo-da-Mavka to the flower. Later, in the time of the Christianization of Kyivan Rus', the flower was renamed to the Ivan-da-Marya. Mavkas are depicted in literature, most notably in Lesia Ukrainka's "The Forest Song" and Mykhailo Kotsiubynsky's "Shadows of Forgotten Ancestors". In modern culture the mavka image is developed and narrated by a Ukrainian music band Mavka