After investigating the alleged miracle of a girl who came back to life after drowning in Australia in 2004, Eko boarded Oceanic Airlines Flight 815.

Lost creators Damon Lindelof and Carlton Cuse were fans of Akinnuoye-Agbaje's work on HBO's Oz, and asked him to portray the character.

They decided a "shocking and emotional death"[1] would be the best way for the character to depart: after seeing his brother on the island, Eko chases him until he stumbles upon the smoke monster, which brutally murders him.

[3] As revealed in "The 23rd Psalm", one day, when Eko is playing with the local children, a gang of guerrillas raids the village in search of young recruits.

[3] Yemi refuses until Eko threatens his associates will burn the church down if he does not sign documents that allow him and his henchmen to appear as priests.

[5] After leaving England, Eko assumes his brother's identity, serving as a priest in Australia under the name Father Tunde.

[6] Eko soon prepares to board Oceanic Airlines Flight 815; shortly after buying a ticket, he encounters the girl whom the investigation is about.

[4][7] In "Adrift", Eko beats Jin-Soo Kwon (Daniel Dae Kim), James "Sawyer" Ford (Josh Holloway), and Michael Dawson (Harold Perrineau) unconscious when they arrive on their beach and hauls them into a pit.

[9] After their arrival in "What Kate Did", John Locke (Terry O'Quinn) shows Eko an orientation video from the DHARMA Initiative.

[10] In "The 23rd Psalm", Eko discovers a Virgin Mary statue in Charlie Pace's (Dominic Monaghan) possession and he demands to be taken to the Beechcraft where it came from, knowing his brother's body is there.

[3] On his fiftieth day on the island, Eko baptizes baby Aaron and his mother Claire Littleton (Emilie De Ravin).

[11] As he discovers the survivors hold one of the others named "Henry Gale" (Michael Emerson) captured in the Swan hatch, he requests to speak to him.

[6] After watching the station's orientation video, Eko vows to continue pushing the button in the hatch, despite Locke's protests.

[13] Desperate not to let the timer run out, Eko goes to the stash of dynamite from the Black Rock, a ship which wrecked on the island before the plane.

[13] Eko's attempt to blow open the blast door has no effect except to knock him unconscious, and he is thus unable to prevent the timer's reaching zero.

[5] Searching for Yemi, he soon decides to follow Locke, Desmond, Sayid Jarrah (Naveen Andrews), Nikki and Paulo (Kiele Sanchez, and Rodrigo Santoro) to the Pearl station.

[5] In one of the flashforwards in the final episode of the fourth season, Hurley is seen sitting at a table with a chessboard on it across from a seemingly empty seat.

[23] Lost creators Damon Lindelof and Carlton Cuse's first choice for the actor to portray Eko was Lance Reddick, after they had seen him as Cedric Daniels on HBO's The Wire.

[24] However, after it was made clear Reddick was unavailable due to the filming schedule of The Wire,[24] Cuse and Lindelof decided to contact Akinnuoye-Agbaje, because they were big fans of his work on the HBO prison drama Oz.

[26] While the producers succeeded in persuading Akinnuoye-Agbaje to take the role, he did not want to make a long-term commitment to the show and was therefore only hired for a short period of time.

While at first Cuse and Lindelof thought this was "the silliest thing in the world", they changed their minds after repeating the name a few times, realizing there "was something really cool about it".

[23] After he had been on the show for one season, Akinnuoye-Agbaje felt uncomfortable living in Hawaii and wanted to return to his residence in London, England.

[47] In response to Mr. Eko's death, Christine Fenno of Entertainment Weekly stated "I'll miss Adewale Akinnuoye-Agbaje—his acting was up there with Terry O'Quinn's, Elizabeth Mitchell's, and Michael Emerson's.