There’s a book, by New Age archeologist Graham Hancock, called “Chariots of the Gods” that says “The pyramids were built by aliens who the ancient Egyptians worshiped as gods.” Some people figured, “Hey, this is a great idea for a movie”, and so they made one.
The movie they made was called “Stargate”. In it, a Graham Hancockish Egyptologist named Dr. Daniel Jackson (James Spader) is called in by the military to decypher this giant metal circle covered with hieroglyphics that the US government uncovered. Jackson discovers that the circle is called a “Stargate”, a device to travel to another planet, and he manages to get it working. So, he and military team, led by Col. Jack O’Neil, go through the stargate to a desert planet inhabited by what appear to be ancient Egyptians. There, they find out that the god Ra was really an alien who came to earth and took the form of a boy, and ruled ancient Egypt, until the people of Egpyt rose up against him. He then used the Stargate, to retreat, along with his followers, to this planet. Unfortunately, Ra is still around, and he wants to take over Earth. Fortunately, Col. O’Neil manages to blow up Ra with a nuclear bomb, the people on the desert planet are set free, Dr. Jackson, who fell in love with a girl there, stays with them, and Col. O’Neil gets his team home.
Ok, so the people who make TV series out of movies saw this, and said, “I bet we can make a TV series out of this”, and they did. The TV series takes place a few years after the movie ends. In it, we find out that Ra wasn’t the only evil alien to take the form of a god, but all the old Egyptian gods were really evil aliens (as were the gods in most other mythologies). It turns out, according to the TV series, they’re a race of evil parasitic eels or something, called the Goa’uld. Adult Goa’uld live in people’s brains and take over their minds, which gives the Goa’uld benefits like opposable thumbs. Baby Goa’uld live in the abdomens of humans the Goa’uld have picked to be their slave soldiers, making the soldiers stronger and more resilient. They also find out that the Stargate doesn’t just go to the planet they went to in the movies, but all sorts of planets. So, in the TV show, Col. O’Neil, Dr. Jackson, another airforce officer named Major Samantha Carter, and this rebel Goa’uld slave soldier go accross the galaxy in the Stargates, fighting the Goa’uld and other bad things that want to take over earth.
After about 7 seasons of this, the creators figured they could get away with trying a sequel/companion series, and that’s Stargate:Atlantis. The setup there is that the original inhabitants of Earth, who lived in the city of Atlantis, somehow became a higher form of life…they “ascended” and became the “Ancients”. But then they were forced to leave earth, and take their city with them, because they were fleeing some sort of alien threat. So, they took their city to another galaxy. Just recently, though, one of the Stargate teams (not the main one), just found a way to get to Atlantis, in the other galaxy, and now they’re stuck there. They’ve got to explore the secrets of the Ancients and fight against the alien threat (that made the Ancients leave), plus find a way to get home.