HK-47 was discovered to be still alive, inside the memory core of a downed Galactic Republic cruiser on Mustafar. He manipulated a group of spacers to free him and raise a droid army. He was later thwarted, but escaped.
Warning: The following section is non-canon. It contains information explicitly released under the Infinities brand, and/or confirmed to be non-canon by the author or Lucasfilm. Everything said in this section and not elsewhere did not happen in the "proper" Star Wars continuity.
↑The New Essential Chronology states that the Ruusan Reformation occurred in 1000 BBY, which is the zero point of the calendar based on the Ruusan Reformation, so the difference between the calendar based on the Battle of Yavin and the Ruusan Reformation's year-notation system is 1,000 years. This date is derived using simple math based upon other confirmed dates.