DICE has a small cast of characters for a series this long and eventful. The list below only leaves out characters that don't have more than a passing influence in the course of events in the series.
Dongtae is the male protagonist of DICE, and the character most often followed by the narrative. He is a second-year student in a nondescript High School. His life is of unending pain and suffering due to incessant bullying, and he has no prospects in life due to his perceived worthlessness. He embraces Dicership as a way of escaping that life.
His goal is to stop the destruction caused by the quests given by X.
Eunju is the female protagonist of DICE and at least initially the object of Dongtae's love. She is in the same year and class as he and her life follows an opposite path with the arrival of Dice: from a popular, upbeat and accomplished girl, she becomes the target of generalised hostility and endures much misery as a consequence.
She is a declared antagonist of X and against Dice.
Taebin is the male deuteragonist of DICE. A transfer student into Dongtae and Eunju's class, he is the one who brings Dice to the school. Behind his veneer of a bright, accomplished and handsome young man hides a past even more miserable than Dongtae's that was also changed by becoming a Dicer. He dated Eunju for a while.
His goal is to stop Mooyoung from becoming the S-Ranker.
Mio is the female deuteragonist of DICE. She is a classmate of the others and begins the story as a bookworm girl lacking in physical traits and confidence who retreats into studying as a way to escape reality. She also becomes a Dicer and is likewise "reborn", although her feelings of insecurity persist.
Her goal is to support Dongtae in whatever he endeavours and eventually win his affection.
Mooyoung is the oldest Dicer revealed so far and Taebin's former mentor. He is extremely powerful and has been described as a "different being". Currently, he contains three 'a-rank' skills. He is constantly scheming to kill all the A-Rankers he needs to harvest the skills missing for him to challenge X again.
His goal is to become the S-Ranker.
Dawn is a member of Taebin's former group of Dicers. She was thought dead as a consequence of Mooyoung's rampage to harvest their A-Rank Dice, but reappeared as a hooded figure in Dongtae's school. She considers Taebin a traitor for allowing Dice to spread further.
A former student in Dongtae's school who failed university entrance exams three times (thus the name). Currently aiding Hood while striving to win the War Quest. Holds a grudge against the school.
A teacher-in-training in the school, the only adult Dicer and an A-Ranker, he is a ruthless player who is delighted at the opportunity to rise to greatness by securing the Final Die. Was the first one to guess X's identity correctly.
A strong A-Ranker who is nevertheless not very bright, he intends to become an S-Ranker to satisfy his petty material desires. He is ultimately wary of direct confrontation and acts by devious ways.
A clever B-Ranker who used to be a chief bully until beaten up by Dongtae. Holds a grudge against him for the humiliation, but hasn't been seen in the story since he was defeated a second time. His name is never revealed in the story.
A very ambitious A-Ranker who originally wanted to humiliate Eunju and replace her as the most popular girl. Later her greed focused on becoming the S-Ranker, but she was ultimately killed in a PVP battle against Sungchul.
A former classmate and fair-weather friend of Dongtae's, he decided to betray him in exchange of an A-Rank Die. Was savagely beaten by Dongtae as a consequence. He ended up dead from injuries in the battle against Miju.
A schoolmate of the protagonists who had no scruples and did whatever he needed to do to become a Dicer and later to gain more power. He became a puppet of Mooyoung and was killed for his A-Rank Die in the end. His true name is never revealed, "Gilma" is short for "guild master".
A classmate of the protagonists and Dongtae's replacement as bread shuttle. Byungchul was a clever young man who went progressively unhinged upon becoming a Dicer. He saw Dice as the ultimate release from the shackles of ordinary life, but he was taken out by X when he successfully hacked into his server.
An underclassman of the protagonists and an A-Ranker. He used to be a fat kid and got acquainted with Dongtae when they were disputing cheeseburgers. Che-Hyun says he is not interested in the Final Die and has cooperated with Dongtae in protecting the school and other people.
The former chief bully in Dongtae's class, he was hospitalised after being hit by Byungchul's Dice-enhanced arm and lost the opportunity to become a Dicer when Dice spread after Byungchul's death. He has since become a weakling relative to the others and has been under Dongtae's protection.
The teacher of Ethics in Dongtae's school. A veteran in the job, he was tired and somewhat scared of the students. Teacher Chun was completely oblivious to Dice and only faintly aware that something odd was happening. He and teacher Kim were often seen talking, but in the end Kim took Chun out during the War Quest.
Dawn, Oh-Hyun, Gibaek, Seyoon and Jihae were a group of Dicers assembled by Mooyoung and Taebin, and the people who got the closest to uncovering some of X's secrets. They were killed by Mooyoung, who had guided them to becoming A-Rankers in order to steal their Dice in the first place. However, Dawn has survived.`