A brilliant scientist and engineer, who traveled with the international expedition led by Dr. Elizabeth Weir to the lost Ancient city of Atlantis in the Pegasus Galaxy. Dr. Zelenka is from the Czech Republic, and is becoming an expert on Ancient technology -- especially the Puddle Jumper ship's systems.
Zelenka is highly respected by his colleagues including Dr. Rodney McKay, especially after he helped to save McKay and the reconnaissance team when their Jumper became lodged in an active Stargate on the way back to Atlantis.
Thirty Eight Minutes - When the team is trapped in a Puddle Jumper lodged in an active Stargate, Zelenka must study another Jumper's systems back in Atlantis to try and save them.
Suspicion - While studying a Puddle Jumper's systems, McKay and Zelenka accidentally discover a command that retracts the roof of the Jumper bay.
The Storm - Zelenka and McKay work together to create a plan to save Atlantis from a giant hurricane by harnessing the storm's electrical activity to power the shield.
Hot Zone - While on a mission to survey flooded areas of Atlantis, Zelenka and his group become exposed to a deadly pathogen.
The Siege, Part 2 - Zelenka and McKay work through the night to complete Genii nuclear devices which will be used on Wraith hive ships threatening to destroy the city.
Duet - Zelenka makes his second trip from Atlantis to help rescue Dr. McKay and Lieutenant Cadman who have become dematerialized inside a Wraith dart.
Trinity - When McKay has unknowingly made a mistake about Project Arcturus Zelenka tries to reason with the arrogant scientist, but to no avail.
Grace Under Pressure - Zelenka joins Colonel Sheppard in a rescue operation to save McKay from a sunken Puddle Jumper.
Allies - Zelenka works on a plan to disseminate Dr. Beckett's retrovirus among the Wraith, and later reports that a computer virus has destroyed the information provided by the enemy.
Irresistible - Radek falls for the charms of Lucius Lavin, who uses chemical pheromones to try and take over the city.
McKay and Mrs. Miller - Zelenka works with McKay and his sister from Earth on an ambitious power-generation project -- which inadvertently allows another McKay from a parallel universe to enter ours.
The Return, Part 1 - When the Ancients return to Atlantis and require the expedition to leave the city, Radek packs up and considers where his future lies back home.
The Game - Zelenka and Lorne end up playing games with Ancient technology, despite the fact that it has already gotten McKay and Sheppard into real-world trouble.
First Strike - Zelenka and McKay are pushed to their creative limits when the city is attacked by a Replicator satellite weapon.
Adrift - Radek must go E.V.A. to make necessary repairs to the city's hyperdrive system, and is injured when a tiny asteroid fragment rips through his leg.
Reunion - Zelenka joins a rescue op inside a Wraith lab when Colonel Sheppard, Dr. McKay, and Teyla are captured.