List of champions with non-american accents?
I can only list

I can only list

REEEEEE
Dammit, beat me to it
I mean, if you're playing with the English-speaking voice actors in mind, then there are really only a few ways it can go - the variety of American, British, the varieties of Irish, Canadian, etc.
I'm like 100% sure the roster sounds Korean in Korea, rather than American.

The majority have no accent. Calling a unaccented voice American seems a bit selective.
There's no such thing as an unaccented voice. Every voice has an accent.
I disagree. One can speak perfect English unsullied by any regional lilts. If such a person were to then speak a foreign language, then there would indeed be an accent, but in the context of champion's English voice-overs, it is accurate to say they are unaccented.
Most champions do not sound American. Champs with American accents are
,
maybe a few more.

Gragas is technically american. Just... really drunk.
Speaking of accents, i want a scottish/irish/italian/spanish accents in league
ehmmm. vayne sounds american tbh

n0000000000000t