Lee Sin
Following the dominance of the jungle by champions building Turbo Chemtank, Lee Sin was one of those who looked to alternatives. The improvements that Riot carried out with this character placed him as one of the best options in League of Legends in three of the five roles, but he finally returned to his natural habitat of Summoners Rift's jungle.
It remains to be seen what happens to Lee Sin in the coming updates, as he has received adjustments that have reduced his performance and we won't have time to see how he plays in a competitive setting before Worlds.
However, if he overcomes the latest Riot changes, he could assert a similar presence to the 85% plus he enjoyed throughout the summer split.
Other candidates
The jungle has had few alternatives of extraordinary dominance, so it is not surprising to find characters like Viego, Xin Zhao, or Diana on the list of possible junglers.
