There is a famous story that Yishayhu Leibowitz used to "skip" Purim. Ostensibly, Leibowitz felt uncomfortable with celebrating a festival that celebrated the Jews slaughtering other people on mass - no matter what the justification for the slaughter.
Since Purim is celebrated in Jerusalem on the 15th of Adar, and in the rest of Israel on the 14th, Leibowitz would travel to Tel Aviv on the night of the 14th. In this manner, he would never be in the city where he would be obligated to celebrate Purim.
BUT is this story true? I've been hearing it for so many years, I assumed it must have a reliable source. However, I've yet to find anyone giving a source for this story. In fact, at least searching online, I constantly come across people doubting the historical validaty of the story. For example Rabbi Nagan tells this same story about Akiva Simon (a peace activist). The Jerusalem Post has an editorial attributing claiming the story is falsly attributed to both Ernest Simon and Leibowitz. In one post on a forum dedicated to Leibowitz, a claim is made that his grandson has recounted celebrating Purim with Leibowitz - but the person does not provide a source for the claim.
This "myth" is so far being rated as "unlikely" but is not yet busted, until I can find a reliable source.