A listener of the science podcast This Week in Virology asked in 2010 whether there are viruses that infect mitochondria:
Is there a virus that infects mitochondria? It’s an organelle that has its own genetic material and polymerase, so it could replicate a virus. Does the mitochondrial double membrane and the cell membrane impose a barrier that phages cannot transpose?
At the time I did not know that there were viruses that infect mitochondria, but they had been discovered years earlier. They are called, appropriately, mitoviruses.