Hive Fleet Kraken

Hive Fleet Kraken was the second Hive fleet of the Tyranids to assault the 40k galaxy and started the Second Tyrannic War which was only stopped when the Ultramarines and Eldar of Craftworld Iyanden defeated the two major prongs of the invasion, although at great cost and not at the destruction of all the splinter fleets of Kraken, which continue to infest and ravage the Imperium to this day.