Bae Oh is the leader of the Ekaterina branch, and Alistair Oh's uncle.
Bae Oh was the younger brother of Gordon Oh, born to Henry Cahill, and Hae In-Oh. Gordon was the only person standing between him and Ekat leadership, so an killer was used to murder Gordon, and wrote him a letter, and that 5 grand would be delivered. Bae faked crying at his funeral, and Alistar was able to see through his lies. Bae took Alistair in, and was mostly disappointed in him, and had his name on a proposed Bae Oh Center of Mechanical Engineering at Harvard to be erected by Alistar. Alistar later split from Bae, and created the microwaveable burrito to Bae's displeasure, and he rejected his nephew who he thought could have promise. Alistair's rocketboard was rejected, and Bae ordered him to be in Istanbul.
In an attempt to get the clues, Bae latter allied with the Madrigal branch, specifically The Man in Black, and William McIntyre. He informed the Man in Black to never contact him directly, instead to use audio links. Bae later caught some Tomas outside the stronghold, and the Man in Black called him, slipping past the now weak Ekat defenses. The Man told him that Grace Cahill was sick, in William told him she was deciding if she should use the version of her will starting a contest to find all the 39 Clues, and that she'll choose Alistair, and if Bae doesn't help, the Ekat's won't win. Bae asks about Amy and Dan Cahill, and the Man in Black said he'll watch them. After learning of Alistair falling asleep in Salzburg, and William's tracking device planted on his cane by Amy and Dan, Bae sent Alistair an angry e-mail.
Later at his house, Bae was going to call Mr. McIntyre, but Alistair began talking to him over the intercom about Gordon's murder. Angry, Bae tried to find his nephew, only to find him gone. He later went to the Ekat stronghold in Egypt, to find Amy and Dan trapped. He told them of the Sakhet's, before locking them in, and later writing a letter to Ekats to start the clue hunt, and to find Alistair.
Isabel Kabra later contacted Bae with news of a fire in Indonesia, and he pinned it on Alistair. While he was captured, Bae and a driver took him away. Suddenly Alistair had heart failure, and Bae reflected on his nephew's 'wasted' life, when Alistair sprang to life, having faked his heart failure, and left Bae, humming a song to Bae's amazement.
Bae is ruthless, and rules the Ekaterina branch, and wants to be a dictator. He will do anything to get power, and wants the Clues for himself to rule the planet. His personality is more Lucian than Ekat.