Peter Grodin was an engineer and adviser to Dr. Elizabeth Weir in Atlantis with the Atlantis expedition. Grodin was British, held a PhD, and was a scientist, as well as a Spanish speaker up until his death in 2005.
While assigned to the Ancient outpost in Antarctica, Grodin studied the Ancients' drone weapons. He was efficient and considerate, often taking Weir's needs ahead of his own, displaying the best traits of a true English gentleman. He was also well-versed in wormhole physics. (SGA: "Rising")
After the Expedition had settled, Grodin worked with Weir to ensure everything was set up, including the proper placement of supplies, quarters, and the removal of all the dead plants. He then worked to shut down the Naquadah generators in order to keep the Shadow creature from feeding off them. (SGA: "Hide and Seek")
After Major John Sheppard's team infiltrated a Hive Ship and obtained the Wraith data storage device, he accessed the information and determined that there was at least 60 Hive Ships in the Pegasus galaxy. (SGA: "Underground")
During the Battle of Atlantis, he traveled in a Puddle Jumper to the Lagrangian Point satellite with Dr. Rodney McKay and Lt. Lou Miller. They successfully recharged and rerouted the power to the satellite's weapon but he was trapped inside. He powered down the satellite until the Wraith were in position and then fired on the first Hive ship, destroying it. This overloaded the circuits and the satellite was unable to fire again. The Wraith then fired on it and he was killed making him the first Human casualty of the Battle of Atlantis with his death leaving the Expedition greatly devastated. (SGA: "The Siege, Part 1")
A few days after McKay was taken by the Wraith, Zelenka recalls that Grodin's death was hard for him to take and he said nothing to anyone else about it. Zelenka remembers that McKay, who had been friends with Grodin, awkwardly tried to comfort Zelenka though it came out more like "when you think about it, we're all probably going to die" which Zelenka had brushed off and told McKay to get back to work. Zelenka regrets his actions when remembering them because while McKay is terrible at such things as giving comfort, he'd tried after Grodin's death despite the fact that it would've been easier for him to do nothing at all. (SGA: "The Lost")
- In an alternate timeline, the "first" time the Expedition arrived in Atlantis, there was no fail-safe to release the city from the ocean floor when the shield failed and the city completely flooded. He attempted to halt the failure of the shield but drowned together with Rodney when Stargate Operations flooded. (SGA: "Before I Sleep")