Participant No. 456. Born April 26, 1974. From Dobong-gu, Seoul. Called "Hyung" by Sang-woo and "Mister" by Sae-byeok. He lives with his elderly mother and works as a designated driver, but leads a self-destructive life, spending his mother's money on gambling and being chased by loan sharks. According to Sang-woo, he is "too kind" and "always meddling in others' business," showing a tendency to help others even at his own expense. He is 47 years old at the time of the game. He has 160 million won in debt and 255 million won in loans.

Participant No. 218. Seong Gi-hun's childhood friend and junior. A brilliant mind who graduated at the top of his class from Seoul National University's Department of Business Administration. During the games, he quickly understands the mechanics, derives optimal solutions, and acts decisively, often providing hints to Gi-hun and the others to clear the games. After the game was suspended by vote, he confessed to Gi-hun that he had invested all of his mother's assets, house, and shop money into derivatives, accumulating 6 billion won in debt. He is also being pursued by the police on charges of embezzlement, forgery of private documents, and fraud. After the game's suspension, he attempted suicide with coal briquettes in his bathtub but regained his senses when the staff rang his intercom, deciding to rejoin the game.

Participant No. 67. A North Korean defector in a desperate situation, needing a large sum of money for her family. Her father died during their defection, and her mother was forcibly repatriated by public security. Her younger brother, Cheol, defected with her and is in a facility in South Korea. Her name, Sae-byeok, means "dawn." Before the game, she worked as a pickpocket and even stole Gi-hun's horse racing winnings. Initially a lone wolf who was wary of everyone, she gradually begins to help Gi-hun and the others. She hates Deok-su. Female.

Participant No. 101. A gangster participant who fled with casino funds and incurred massive debts through organizations and gambling in the Philippines. He has a cold and selfish personality, attempting to dominate others through fear and violence. Male.

One of the 456 players competing in the life-or-death game for the 456 billion won prize. She tries to ingratiate herself with or manipulate other players to survive, often acting coquettish toward men. She had a sexual encounter with Deok-su. No. 212.

A character who remains somewhat detached and cynical even in dire situations, yet possesses a deep spirit of self-sacrifice and warmth hidden within. She has a traumatic family background (a dark past involving her father) and feels a profound sense of despair toward life. She shares a bond of mutual understanding with Sae-byeok. Female. No. 240.

An extremely pure and polite person who builds a relationship of trust with Seong Gi-hun after saving him in the first game, "Red Light, Green Light." He came to South Korea to support his family but was put in a difficult position after his employer withheld his wages for over six months. He calls Sang-woo "Hyung." No. 199.

An elderly man suffering from a brain tumor with little time left to live. He claims he participated because he had nowhere to go in the outside world and wanted to enjoy the pure nostalgia and thrill of the games rather than out of fear. He forms a "Gganbu" (best friend/partner) bond with Seong Gi-hun. While portrayed on the surface as a helpless old man with a brain tumor, he is actually one of the creators (the mastermind) of the death game. No. 1.

The leader of the Squid Game, who hosts and manages the competition where people with massive debts compete for a 456 billion won prize. Throughout the series, he is depicted as a cold individual who does not show emotion. He is the Front Man of the Squid Game.

Also known as Pink Men or Staff. - Square (Leader): The highest rank. Issues orders to Circle and Triangle staff. - Triangle (Soldier): Armed personnel permitted to carry firearms. Responsible for monitoring and executing participants. - Circle (Worker): The lowest rank. Responsible for chores, cleaning up bodies, and distributing meals. They are the operational force wearing pink jumpsuits and masks with circle, triangle, or square symbols. Their authority and roles differ by rank, covering participant management, execution, and body disposal.