Ethan Rom is a fictional character portrayed by William Mapother on the ABC television show Lost.

Ethan is one of few people known to have been born on the island, as seen in the ninth episode of the fifth season, "Namaste".

By the time he was 11 (1988), Ethan had joined the Others and assisted Ben in kidnapping baby Alex from Danielle Rousseau.

Ethan claims to have lived in Ontario, Canada, for some time[3] but this was part of his alibi to the Flight 815 survivors.

Around three years before the crash, he travels from the island to Florida by submarine to recruit Juliet Burke, with the help of Richard Alpert.

He takes blood samples to determine if Claire is encountering pregnancy issues and goes on hunting trips with John Locke.

Knowing that he will be exposed before he can complete a list of the survivors, Ethan kidnaps Charlie Pace and the pregnant Claire Littleton for scientific research.

When Ethan arrives to take Claire, Locke, Jack, Kate, Sayid, and Sawyer run in and tackle him down.

William Mapother did not audition for the part; he was chosen by co-creator/executive producer J. J. Abrams—who recognized him from the film, In the Bedroom—on September 22, 2004, the day that Lost premiered.

In the first season, Ethan was portrayed as a "brooding villain", "cold and evil" and "creepy" and after as a "swell, neighborly guy".