P9J-333 was a planet in the Milky Way galaxy which held a Stargate. In 2006, as part of the Ori invasion of the Milky Way galaxy, the people of the planet were visited by a Prior, who was attempting to convert the people to Origin. As such, Teal'c was sent with SG-3 to the planet by Stargate Command, using modified Sodan Invisibility devices to monitor the people.
While SG-3 were on the planet, a strange creature started to attack and slay the local people. As such, SG-3 broke their cover in an attempt to save the locals. The Tau'ri team at first believed that this was initiated by the Ori, to kill any non-believers on the planet, but it was later discovered that it was caused by an Interdimensional parasite which came to the planet due to SG-3's use of the modified Sodan devices. Once this parasite infested the local wildlife, it transformed them into rabid carnivores which attacked entirely at random.
Though this was the first planet on which the interdimensional parasite was discovered, it soon appeared on P2R-866 and Earth as well. SG-1 arrived on the planet to assist SG-3 and, through their combined efforts, they were able to kill the mutated creature. It was because of this that the SGC's scientists were able to discover the existence of the interdimensional parasites. (SG1: "Uninvited")