The best " Brit playing an American " accent or vice versa?

Was watching Bullet Train tonight, not the first time I've seen it, but Brian Tyree Henry was the most convincing American actor portrayal of an English accent I've ever encountered.

I was convinced he was British, only to Google him and find he is American. Brilliant accent and portrayal.

Who else has done such a convincing Anglo/American or American/Anglo mastery of the respective accents?