Og: Lord of the Giants

There are plenty of 'giant' champions. Not giant as in the race, but there are absolutely massive champions lore-wise. Everything is scaled-down in game for obvious reasons. If not, Aurelion Sol would be ten times the size of the map, and so would champs like Malph.

All of these champions (maybe not Ornn) are MASSIVE. Varying from titanic status ( Galio, A.Sol, Malphite ) to 'much larger than average human' ( Zac, Sion, Nautilus ).

The concept of a 'giant' is usually just a big guy. Humanoid, typically doesn't look too too different from a human. Considering we scale things down in game, there'd be hardly any difference between our 'giant' and someone like Darius.

I guess what i'm trying to say here is Sion is what you're looking for. Play Sion.