Ragnar Lodbrok is according to the tale with the same name, the son of a Swedish king named Ring, who also rules over Denmark. According to some sources, Ragnar has been identified as a Danish Viking who plundered Paris in the 9th century. Ragnar gets his nickname Lodbrok after he, dressed in a special kind of protective wolfskin trousers, rescues his first wife Tora from a huge serpent surrounding her home. Ragnar is killed during a conquest in England, when the Saxon king Ella throws him into a snake pit. His adult sons then revenge their father by killing Ella.
The Saga of Ragnar Lodbrok in English:
http://www.turbidwater.com/portfolio/downloads/RagnarsSaga.pdf