Kat Von D Sued Over Cat Killing Fire

State Farm Insurance filed the lawsuit against Kat today in L.A. County Superior Court, claiming the 2010 fire that ripped through the reality star's Hollywood Hills home was her own fault ... and she should foot the bill.

According to the lawsuit, Kat foolishly placed several lit candles in the house -- and the candles then set the house on fire (a fire that killed Kat's feline friend named Valentine).

It was no small blaze either -- State Farm claims the fire caused $909,199 in damages.