Black Bolt
It was revealed in "" that Black Bolt had been replaced by a Skrull impostor for an unknown amount of time. The impostor revealed himself to the Illuminati and was killed. Both the sudden rift between Medusa and Black Bolt apparent in "Silent War" and Black Bolt's later defeat at the hands of Hulk in "World War Hulk" could be attributed to this development, for it is uncertain just when Black Bolt might have been replaced by his Skrull duplicate.