June 2011 – MyBitcoins Hack

mybitcoins

In August 2011, MyBitcoin, a now defunct bitcoin transaction processor, declared that it was hacked, which caused it to be shut down, paying 49% on customer deposits, leaving more than 78,000 bitcoins (equivalent to roughly US$800,000 at that time) unaccounted for.

July 2011 – Bitomat Hack

bitcoin7.com

October 2011 – Bitcoin7 Hack