- The younger brother of Peter and Valentine, at age six Ender is chosen by Colonel Graff and the International Fleet to help save mankind from the buggers. Ender is afraid of his brother and loves his sister. Wherever he goes, Ender makes things happen, and by age nine he is given his own army to command. Ender is angry at the various people who manipulate him throughout the novel.
in-depth analysis of Ender.
- Ender's older sister is the only person in the world who truly loves him. She protects him from Peter, their sadistic older brother. Along with Peter, Valentine takes an active interest in the world's political situation, and writing under the pseudonym Demosthenes begins to exert influence over the growing situation. Valentine also writes a letter to Ender at one point that helps him get control of himself. At the end of the book, Valentine convinces Ender to go with her to colonize the bugger worlds, and she works on a history of the world on the way there. Later she travels with Ender as he searches for a new world for the buggers.
in-depth analysis of Valentine.
- Ender's older brother Peter is a cruel and evil child, gifted in manipulation. He has the same ruthlessness that his siblings contain but without any of their compassion. Valentine is able to protect Ender as best she can from Peter until Ender goes away. Peter then decides to take an active role in world affairs and convinces Valentine to help him. Under the pseudonym Locke he begins to gather power, working through the communication nets. After Ender's victory Peter obtains total control of earth and becomes Hegemon, the ruler of the world. His ambition is sated and he actually makes for a good ruler, although he is as amoral is he ever was.
in-depth analysis of Peter.
- Graff has unerring faith in Ender and, although he manipulates Ender, he also loves him. Graff is the head of the Battle School until Ender leaves, at which time he accompanies him until he passes off the training of Ender to Mazer Rackham. He is one of the few characters who at various times allows Ender to act like the child he is, although Graff also demands much of Ender. He is put on trial after the war because of the deaths of Stilson and Bonzo but acquitted.
- Ender's last teacher, Rackham makes no attempt to become Ender's friend, although, like Graff, he loves and respects the boy. Rackham is forced to deceive Ender into thinking he is playing mere games and explains to him that no one but a child could have won the war—it took both compassion, daring, and ruthlessness that he himself could not have had since he knew it was not a game.
- Second in command only to Colonel Graff at the Battle School, Major Anderson is in charge of setting up battleroom scenarios. He stacks the odds against Ender, and Ender views him almost as an enemy, but, like Graff, Anderson feels for Ender. He questions some of Graff's actions but stands by him during his trial.
- Ender's last friend at Battle School, Bean is very reminiscent of Ender when he first arrived. Bold and brilliant, Bean helps Ender with Dragon Army and also helps him hold on to his humanity. He is one of Ender's commanders against the buggers.
- A member of Ender's launch group, Alai becomes Ender's best friend and helps him gain acceptance with the other recruits. Several times his friendship is enough to keep Ender from falling into despair. Later on he is one of Ender's commanders in the battles against the buggers.
- Ender's platoon leader in Rat Army, Dink is a very good strategist who always looks out for Ender. He tries to stop Bonzo and warns Ender of the plot to kill him. Dink is one of Ender's squadron leaders in the battles with the buggers.
- While in Salamander Army Petra helps Ender learn how to fight in the battleroom. They remain friends through the rest of the book, even though she is upset when his Dragon Army defeats her Phoenix Army. She is one of his commanders in the battles with the buggers.
- Bonzo is Ender's enemy and was the commander of Salamander Army. His pride cannot accept the fact that Ender is smarter and better than him, and this makes him cruel. His honor forces him to fight Ender man-to-man, and Bonzo is killed in that fight.
- Bernard has his arm broken by Ender on the shuttle ride over because he attacked him. Bernard tries to bully the launch group into disliking Shen and Ender. Bernard is one of those who went with Bonzo to corner Ender in the showers.
- The bully who attempts to gang up in Ender back in the days before battle school, he is unintentionally killed by Ender in a fight. Ender learns that he killed Stilson while watching the tapes of Graff's trial.
- A small recruit in Ender's launch group who becomes a friend of Ender's through their mutual dislike of Bernard. Shen is one of Ender's commanders in the battles with the buggers.
- One of Ender's toon leaders in Dragon Army, Crazy Tom takes the initiative well and thinks quickly on his own. He is one of Ender's platoon leaders during the battles of the Third Invasion.
- He is one of Ender's toon leaders in Dragon Army. Fly Molo is also with Ender during the battles against the buggers.
- Han Tzu is another of Ender's toon leader from Dragon Army. He works again with his commander in the war with the buggers.
- The commander of Rabbit Army, Carn Carby treats Ender well even though he is beaten badly by Dragon Army. He is one of the platoon leaders in the Third Invasion.
Rose the Nose
- Ender's commander in Rat Army, Rose the Nose tries to control Ender. Largely due to Dink's suggestion that he stick up for himself, Ender is able to make Rose the Nose back down and he lets Ender be.
- The chief of the I.F. military police, Pace wants Graff to do something about the plot to harm Ender. Graff wins out, and Ender saves himself, although Bonzo dies in the fight.
- The only teacher assigned by the school to actually befriend the Launchies, Dap looks out for the boys. He informs General Pace of the plot against Ender.
- The leader of the fleet, Chamrajnagar questions the three month vacation that Graff let Ender have and then fills Graff in on their plans for Ender at Command School. He and Graff have a mutual dislike but respect each other.
- The computer expert at the Battle School, Major Imbu explains to Colonel Graff what he knows about the mind game. He tell Graff that the game showed Ender the picture of Peter because it thinks that is what he needed to see, but also that it is making the game up as it goes along.
- A high military official, he takes interest in Ender and questions Graff as to how he will bring him along. Levy points out that the children at the Battle School do not act like normal children, and Graff says that they are not.