User blog comment:HozzieHozzbourne/Strongest champion outside of the game/@comment-5763148-20130920133858

I would say the 5 most powerful Champions, lorewise, are: Kayle; Morgana; Nasus; Cho'Gath and Renekton.

They are all entities and beings that are very ancient and of a high power. Kayle and Morgana are angels that have been around for thousands of years, Nasus and Renekton have extremely ancient background and Cho is the very embodiment of the Void.

I guess Aatrox is also a viable entity in that respect and can replace Renekton's place since he has been around since the time of 'War', but we need to have more info on Darkins before making any conclusions.