The most puzzling is the one from Mt. Gox so far.

This is a summary of the most significant cryptocurrency thefts since 2009, based on available information and ordered by their magnitude at the time of the theft (in US dollars). The values are adjusted to the time of the incident, although some cases, such as Mt. Gox, would have a much greater impact at current prices. I include key details of each case, such as the affected platform, date, amount stolen, involved cryptocurrencies, and the circumstances of the attack.