The oldest version of a legend about the dragon of Wawel, related to the mythic beginning of Cracow, can be found in the Chronicle of Master Vincent called Kadlubek (from the turn of the 13th century):
”In the tun nels of a certain rock there lived an immensely dreadful monster, whom some used to call the whole-eater. Every week his voracity called for a fixed number of cattle. If the settlers had not supplied the cattle (as sacrificial beasts) they would be punished by losing the equivalent number of human heads. Grakch [Cracus] could not tolerate the shame of this [...] and he secretly called his sons, told them of his intention and presented a solution [...] To which they answered: [...] ‘It is you who has the power to give orders, and we are here to obey’.
"Having experienced many, and generally futile, skirmishes, they were forced to use deception. In the place of the cattle they put cattle’s skins stuffed with ignited sulphur. And when the whole-eater swallowed it with great appetite, he suffocated from the outburst of an internal fire. Immediately after this, the younger brother attacked and killed the older, his partner in victory and in the kingdom, treating him not as a companion but as a competitor. He lied that it was the monster who was guilty of the killing, and his father happily accepted him as a winner. Thus the younger Cracus succeeded his father, benefiting from his crime! But he was tainted with fratricide longer than he was awarded with power. Soon after, the deceit came to light, and as punishment for his deed, he was banished forever[...]”
”And it was indeed on the rock of the whole-eater that the famous city was soon established, named Cracovia from Cracus’ name, to commemorate him forever. The funeral ceremony finished only when the city was completed. Some named it Cracow because of the crowing of the crows, who flew in attracted by the carcass of the monster.”
Jan Dlugosz changed this version of the legend by writing that it was King Cracus himself who killed the dragon. At the end of the 16th century Joachim Bielski introduced the character of a sly cobbler Skuba to the legend, and this is the most popular version nowadays.