User blog comment:HozzieHozzbourne/Strongest champion outside of the game/@comment-1330314-20130920084540

Nasus and Renekton are both godlike figures, and are powerful enough to scare summoners, who can handle other champions far more easily. Noc is the living embodiment of nightmares, and in one possible future turned the world into his own evil dimension (Eternum Nocturne). Similarly, Karthus is capable of killing all life on Runeterra by singing his Requiem in full.