Lina Mayfleet, one of the two protagonists in the novel, wants to be a messenger. On Assignment Day, each graduate randomly chooses a job out of a bag. Lina wants to be a messenger because she wants to run and carry messages throughout the city because she is quick on her feet, and wants to explore the city. The slip of paper she picks reads: PIPEWORKS LABORER. Lina is disappointed because she will work underneath the city. Doon Harrow, one of her friends, recieves the job messenger. They eagerly trade jobs.
Poppy Mayfleet
Poppy is Lina's younger sister. She finds a box containing a paper and unknowingly rips it up and starts to eat it because she is only a toddler.
Mayor Cole
Mayor Cole, the mayor of Ember, promises his citizens that he has found solutions. Doon discovers a hidden door in the pipeworks that has been roped off. Inside, there is a room full of all the items and foods anyone could ever want. Doon sees the mayor asleep in a chair in the center of the room, and he exits, then tells Lina what he saw. The mayor is taking the food from the people of Ember, and telling them that there are solutions. Even though his solution is to take supplies for himself, leaving everyone else starving.
Doon Harrow
Doon Harrow, the other of the two protagonists in the novel, wants to be an electrician's assistant, because he believes he can fix the failing generator and stop the blackouts in the city. The slip of paper Doon picks says: MESSENGER, and Doon trades jobs with Lina because at least he will work underground where he will be close to the generator.
Evaleen Murdo
Evaleen Murdo is the second guardian of Lina and Poppy and cares about them very much. She had taken them in because their grandmother had gotten ill and passed away. At the end of the novel, Mrs. Murdo finds the message that Lina and Doon dropped into Ember.
Looper
Looper is a teenage boy with a long neck and large teeth. He steals lots of supplies from the storerooms, which he sells in his shop or secretly delivers to Mayor Cole. He is Lizzie (Lina's best friend)'s boyfriend and shares some of his stolen items with her.