Koro-sensei: The primary target and homeroom teacher of Class 3-E. He is a yellow, octopus-like creature capable of moving at speeds up to Mach 20. Despite threatening to destroy Earth, he is an incredibly caring mentor who helps his students excel both academically and in the art of assassination.

Nagisa Shiota is the main character. He is small and quiet. He looks like a girl with blue shoulder-length hair. But he is a natural assassin. He hides a fierce spirit. He tracks the teacher's flaws. He is very brave.

Karma Akabane is Nagisa's friend. He is very smart. He is a rebel. Karma loves to fight. He is a skilled fighter. He is very tricky. He hurt Koro-sensei first. He loves to pull pranks

Kaede Kayano is a cheerful girl. She loves eating pudding. She is Nagisa's friend. She stays by his side. But Kaede hides a secret. Her real name is Akari Yukimura. She wants revenge on Koro-sensei.

Tadaomi Karasuma works for the government. He teaches gym class. He teaches kids to fight. He is very strong. He is always serious. Irina Jelavić is a professional killer. She teaches foreign languages. The kids call her "Bitch-sensei." She is good at undercover work. Both teachers protect the class

Yuma Isogai is the male class representative. He is polite, well-liked, and works hard to support his family. Hiroto Maehara is Isogai's best friend. He is very social and agile. Both are among the top knife fighters in the class and work perfectly as a team.

Megu Kataoka is the female class leader. She is very athletic. She is very responsible. She acts like a big sister. She is great at swimming. She keeps the girls organized during missions.

Manami Okuda is a shy girl. She is a chemistry genius. She makes deadly poisons. Rio Nakamura is a prankster. She is also very smart. She speaks English well. She teases Nagisa often

Ryunosuke Chiba and Rinka Hayami are snipers. Chiba hides his eyes. Hayami is calm and accurate. Tomohito Sugino plays baseball. He throws weapons like baseballs. Yukiko Kanzaki is gentle and kind. She is a master at arcade games.

Ryoma Terasaka is a big bully. He starts out lazy. He dislikes the class mission. Later, he changes. He becomes a good friend. He uses his strength to protect others.