Stargate - Alpha One
Supreme Commander of the Asgard Fleet
Thor was on his way to visit Earth and some other of the protected colonies when he discovered that a Replicator ship had followed him to the Milky Way galaxy. In order to protect the humans of Earth, Thor self-destructed his ship, the Beliskner, taking the replicators with it.
Thor himself survived, and was stranded on the planet Earth, without a means of contacting his fellow Asgard. To make matters worse, Baal detected the explosion and traced it to Earth. He discovered one surviving fragment of the ship and decided to claim it as his own. Thor himself had transported down to the planet’s surface before the explosion, but did not have the resources he needed to take it back from Baal.
Thor spent the next 30 years hiding from the humans who believe him to be their enemy – this is exactly what Baal desired. The rest of the Asgard believed him to be dead, and had replaced his hologram on Cimmeria with one of Odin.