Dr. Zager (Japanese: ゼーゲル博士 Dr. Seger) is a Team Rocket scientist. He made his debut in Scraggy-Hatched to be Wild! as a minor character, but later became a recurring antagonist.
After the Team Rocket trio stole a meteorite from the Nacrene Museum in The Battle According to Lenora! by switching the real meteorite with a fake one, the trio encountered Pierce with Dr. Zager in Scraggy-Hatched to be Wild!. They gave the meteorite to the doctor, who analyzed it and found out that the meteorite contained materials not found on their planet.
He made another appearance in A Venipede Stampede! with Jessie, James, Meowth and Pierce in a helicopter above the Desert Resort, where they finally found the Meteonite. In Team Rocket vs. Team Plasma!, he helped retrieve the Meteonite from Relic Castle and accomponied Giovanni as he attempted to take over Unova. When the plan hit a setback, Zager went back to Kanto along with Giovanni and Pierce.
Following the events of Battling For The Love of Bug-Types!, Zager appears to have taken on a commanding officer role in relation to Jessie, James and Meowth; this relationship is not unlike the one between Dr. Namba, Butch and Cassidy. He is often seen coordinating the trio's missions and giving them advice on how to accomplish their objectives. He has also provided them with several machines and weapons of various kinds. The trio report to him and are often tasked with collecting Pokémon for his experiments.
In Scare at the Litwick Mansion!, he appeared on a video call speaking to them, advising them of the danger posed by the Litwick inhabiting the Litwick Mansion. He claimed to have done extensive research on the Pokémon.
Zager is mentioned by Jessie and James in Gotta Catch A Roggenrola!. He designed the Roggenrola-powered laser cannon they use in the episode and tasked them with collecting many Roggenrola to power it.
He appears as an overhead vision Where Did You Go, Audino? when Jessie and James were discussing their plans for their captured Audino. He was mentioned to be conducting an experiment to create a radar system using the Audino and their remarkable hearing.
In Archeops In The Modern World!, he coordinated Jessie and James's collection of the Dream Energy from Fennel's experiment. At the end of the episode, he hinted that he would use it in conjunction with the energy Jessie and James collected from the Dreamyard in Dreams by the Yard Full! to create his own copy of the fossil regeneration system.
Though he did not appear in person, he was mentioned by Jessie and James in Meowth's Scrafty Tactics! and arrived in Anville Town in Purrloin: Sweet or Sneaky?. He appeared in The Beartic Mountain Feud!, where he warned Jessie and James to beware of Subway Boss Ingo and his brother Emmet. Zager then appeared in To Catch a Ghost Train! and BW048, where for the first time, he took on the role of direct antagonist. After scrambling the electronics of Nimbasa City and shutting down Driftveil Drawbridge, he appeared in a helicopter and attempted to capture the subway car containing all of the stolen Pokémon using a claw attached to his helicopter. However, he was thwarted when Pikachu broke the claw with Electro Ball, forcing him to flee and order Jessie, James and Meowth to withdraw.
Dr. Zager made another appearance in BW056, where he introduced Jessie, James and Meowth to their mission to capture Tornadus, Thundurus and Landorus on Milos Island. In BW060 he appeared again, piloting his helicopter in once Jessie, James and Meowth had captured the Kami trio to pick them up. However, when Ash, Iris and Cilan attacked the helicopter as a group and damaged it, he was forced to jettison his cargo of the three Legendary Pokémon and escape.
He made another appearance in BW075, where he met Ash face-to-face for the first time. Using the data stolen from Fennel's fossil regeneration machine in conjunction with the electrically-charged rocks he had Jessie, James and Meowth steal from Chargestone Cave, he fulfilled his earlier stated goal of creating his own fossil regeneration device. While holding off Ash and Fujio using a barrier inside his helicopter, he used the machine to restore the Tirtouga fossil stolen from Fujio. He will also appear in BW076, leading the trio to recapture Tirtouga to use its energy for finding a time portal inside Twist Mountain. He also appeared in BW076, leading the trio to recapture Tirtouga to use its energy for finding a time portal inside Twist Mountain. When they failed, he escaped once again in his damaged helicopter.
Dr. Zager appeared again in Rocking the Virbank Gym! Part 1. He was seen speaking with Jessie, James and Meowth about their mission to capture Meloetta. Because of the Melody Pokémon's ability to turn invisible, Dr. Zager mentioned that he was developing special goggles to detect it. In Piplup, Pansage, and a Meeting of the Times!, he was seen in his submarine laboratory with Jessie, James and Meowth, analyzing their recording of Meloetta's singing. Pleased with the results of the experiment, they decided to report it to Giovanni and mentioned that the song could be used to break a seal on the Abyssal Ruins.
He appeared again in Goodbye, Junior Cup - Hello Adventure!, assisting Jessie, James and Meowth in finding the entrance to the Abyssal Ruins. In Unrest at the Nursery! he was seen once more in his submarine lab, putting the finishing touches on the preparations for Team Rocket's "Operation Tempest." He appeared in Meloetta and the Undersea Temple! to assist Giovanni in reaching and activating the temple, and appeared again in Unova's Survival Crisis! to play a similar role. After the plan failed, he retreated back to the Kanto region along with Giovanni, Jessie, James and Meowth.
His final appearance to date is in the last end credits of "Best Wishes", in which he is shown on a screen presenting the blueprints for Jessie, James and Meowth's Basculin-shaped submarine to them.