Learn English – What do you call a person who hates everyone but himself

A trend-setter or trendsetter:

someone who starts a trend, or makes one more popular

The other answers on this page have a couple other fine suggestions — and a thesaurus lookup turns up more suggestions still —, but be aware that some of them require additional quali­fication. For example, it's typically "a harbinger of something", or "a precursor to something". So you won't be able to just say "he is a harbinger" and leave it at that; likewise, "he is a pre­cursor" will only raise questions if no further context is supplied. "He is a trendsetter", on the other hand, is perfectly self-explanatory and self-sufficient.

A "goody two-shoes" is one possibility. A "saint" is another. A regular [This word makes the appellation ironic] "Mother Teresa". A "fraud" or a "one-dimensional fictional character" [There's nobody who's "never done anything wrong in their life"].