One of the most prominent cancers are Leblanc, Nidalee and Irelia, which are also referred to as "The Unholy Cancerous Trinity of LoL". Usually, the people who main these champions usually suffer from Autism or Intellectual disability.

Leblanc: The high ap burst cancer that causes grief when played against. Not only does this champion have an absurd amount of mobility, this cancerous cancer cannot be stopped in a 1v1 scenario if she has an early lead. Also, Leblanc is one of the most leading ap cancers that makes Riot remove certain items like DFG(DeathFire Gras), so there will be more "counter play" and survivability for squishy champions. The sad reality it is partly Leblanc's fault items get removed and the game's diversity gets trampled.

Irelia: The sole reason Riot had to remake Doran's blade to give 3% "life-steal", because Irelia's W passive gave too much hp back with the old Doran's blade. Not only did Irelia singlehandedly managed to remake one of the most important early game items, she also is the leading cause why the Defensive mastery tree is less effective for bruisers. She literally makes everything worse just by existing.

Nidalee: This cancer holds the title of being one of the most anti-fun champions to play against in the entire game. Nidalee possesses a kit designed to frustrate her opponents to wrist-cutting marathons, she has enough mobility to outrun Usain Bolt, she is able to literally one shot an ad carry in the late game and also is able to restore half of someome's health for a relatively small cooldown. The only solution to Nidalee is to remove all her skills and ban all Nidalee mains from the game.