There has been a lot of research on non-violent resistance, but looking at Wikipedia's page on the topic, I can't seem to answer this question: What was the first non-violent toppling of a dictator?
N.B.: there is a related but not identical question here What was the first successful non violent independence movement? It gives India as example, but arguably India didn't topple a dictatorship then.
The oldest one mentioned in Wikipedia that seems to unambiguously qualify is perhaps the 1986 People Power Revolution in the Philippines. But this seems awfully recent. Are there any older examples?
And since people have quibble about terminology "toppling" is a term used by one of the scholars in this field. (And so is "dictator" and "non-violent".)