Peter Kavanagh

Kavanagh was a civilian scientist who worked previously in the Atlantis Expedition before transferring back to Earth after the seige.

Synopsis
Kavanagh was originally part of the SGC and joined the Atlantis Expedition because he thought things would be more to his liking with a civilian leader instead of a military one.

When John Sheppard's team in a Puddle Jumper was stuck in an active Stargate, he was part of the team working on a way to help them. He got into an argument with Dr. Simpson about the possibility of the Jumper exploding and the burning fragments entering the Gateroom like bombs. She thought it was a very remote possibility, but he thought it wasn't. The other scientists and Doctor Weir sided with her. After Weir told him to "Worry a little bit more about their lives, and less about your own ass," he accused her of humiliating him in front of his team. She threatened to exile him to a barren world alone if he didn't return to work. In the end, however, his idea of blowing up the rear hatch of the Jumper to get forward momentum, helped the ship come through the gate.

When everybody was asked to record a personal message to send to the loved ones on Earth, he instead choose to record one to General Jack O'Neill, detailing everything he thought Weir had done wrong since their arrival.

In a discussion over whether to stay and fight, he believed that 200 people, mostly "scientists who’ve never even fired a gun before", were no match for tens of thousands of Wraith without the City's shield or primary defenses. Doctor McKay was surprised to find himself agreeing with Kavanagh.

He left Atlantis after the siege. He returned a few months later but requested to leave again just three weeks after that because he didn't feel welcome.

He was aboard the Daedalus en route to Earth when the message of a Trust agent having infiltrated Atlantis arrived. He was their prime suspect in sabotaging the city, but he was found innocent. He was threatened by Ronon Dex to give up the code needed to save the base (the one he didn't know), but he fainted before Ronon even touched him.

During the episode "Midway", Kavanagh returned as a part of the Midway station crew, with a shorter hair cut. During the invasion of the Midway Station, the Wraith held him hostage (once again, he promptly fainted in fear). He caused and survived the destruction of the Midway Station, escaping in a Jumper escape pod with the others and rescued by the Daedalus.

After the events on "Midway", Kavanagh's current whereabouts are unknown.