From the Snowden leaks to Adobe's loss of 38 Million passwords,this article runs through some of the most significant security breaches and cyber attacks in 2013.
Don't forget the Target credit card leak. Possibly worst of all because it ahem targeted physical credit and debit cards.
Great point Adyus, I think that and the Snapchat Breach were two that nearly made this list. Physical security is one of the most overlooked parts of a security plan.