Einstein's biggest involvement with the bomb was convincing Roosevelt that the Germans were working on nuclear weaponry and we needed to beat them to the punch. That was his only direct involvement with the Manhatten Project. I've always had a pedestrian interest in the development of nuclear weaponry, and Oppenheimer was at the head of it all.

I didn't list Einstein simply because I didn't feel like being redundant.

Gandhi, because he's one of the most insipirational figures in human history. I suppose I'd also add Desmond Tutu to the list, now that I think about it.