Jiraia (real name Danzou Tobita) is the most feared ninja in all the lands. He was the strongest man in the Oniwabanshu, the one who created the Hyakka, the founder and chief of the Hundred Blooms as well as Tsukuyo's master. He was born in the countryside to Iga samurai. From a young age he had a talent for ninjutsu and so went on to become a ninja, but was forced to work under the people he hated. To try and escape reality he kept on fighting, eventually becoming known as 'Jiraia the Spider' because of his spider like instincts and fighting technique. His name is based on Jiraiya, a ninja of Japanese folktale.

Source - Wikipedia.