List of Halo characters

Major recurring characters of the Halo multimedia franchise are organized below by their respective affiliations within the series' fictional universe. The franchise's central story revolves around conflict between humanity under the auspices of the United Nations Space Command or UNSC, and an alien alliance known as the Covenant. The artifacts left behind by an ancient race known as the Forerunner play a central role—particularly the ringworlds known as Halos, built to contain the threat of the parasitic Flood.

The characters underwent major changes over the course of the first Halo game's development, and were continually refined or changed with the advance of graphics and animation technologies. Halo's commercial and critical success has led to large amounts of merchandise featuring the franchise's characters to be produced. The Master Chief, the most visible symbol of the series, has been heavily marketed, with the character's visage appearing on soda bottles, T-shirts, and Xbox controllers. Other merchandise produced includes several sets of action figures. The franchise's characters have received varying reception, with some praised as among the best in gaming, while others have been called cliched or boring.

The Halo franchise originated with the 2001 video game Halo: Combat Evolved. The game's characters were continually refined through development, as developer Bungie was bought by Microsoft and the platform shifted from the Macintosh to the Xbox. Other Bungie developers would often add input to character development, even if they were not working on the game itself. An outside artist, Shi Kai Wang, developed the early concept sketches of what would eventually become the Master Chief. However upon developing a 3D model, the artists decided the Chief looked too slender, almost effeminate, and subsequently bulked up the character. Early Covenant Elites had a more natural jaw rather than the split mandibles they would later sport; at one point, Jason Jones was also insistent about having a tail on the Elites, but this idea was eventually dropped.

Originally, the game designers decided to hand-key character animations. The animators videotaped themselves to have reference footage for the movement of game characters; art director Marcus Lehto's wife recorded him "running around a field with a two-by-four" for the human marines. By Halo 3, Bungie staff had a special room designed for capturing reference material. Many of the subsequent human character's features were based on Bungie designers, while character animators looked to simian, ursine, insectoid, and reptilian features for the various races of the Covenant. The artificial intelligences of the characters was also deliberately limited to make sure they acted realistically to environmental changes and situations. Later games use motion capture to capture the movement and facial acting of the cast.

The Halo series features voice work by television and film actors including Ron Perlman, Orlando Jones, Michelle Rodriguez, Robert Davi, and Terence Stamp. Voice acting became more important as Halo: Combat Evolved's sequels were developed; Halo 2 had 2,000 lines of combat dialogue, while Halo 3 has in excess of 14,000 lines. Some actors voiced their lines in remote locations, while others traveled to a studio to record their lines. In interviews, Halo's voice actors stated that they had no idea that the games would become such a critical and commercial success. Steve Downes, the voice of the game's protagonist, stated that generally when a voice actor has finished their lines, their involvement with the game ends. As the characters in Combat Evolved were relatively undefined, the voice actors were given leeway to develop their own style and personality.

Aside from major character roles, members of the Halo community and Halo fans have had small roles in the games. The cast from the machinima Red vs. Blue won a lengthy charity auction for a voice role in Halo 3, and do a comedy routine which changes depending on the difficulty level the game is played on. Cast members of the defunct TV show Firefly—Alan Tudyk, Nathan Fillion, and Adam Baldwin—have roles as marines in Halo 3 as well as Halo 3: ODST and Halo 5: Guardians.

Master Chief Petty Officer John-117, commonly referred to as simply the Master Chief, is the main protagonist and main playable character in many of the Halo games. The character is voiced by Steve Downes, a Chicago disc jockey. He is one of the Spartans, an elite group of augmented soldiers raised from childhood to be super soldiers. Assisted by the artificial intelligence Cortana, he prevents the catastrophic firing of the Halo Installation 04 in Halo: Combat Evolved. Developing the character of Master Chief was part of Bungie's efforts to make players invested in playing the game. The character has since become a gaming icon, the mascot of the Xbox, and rated as one of the greatest characters in video games. In live action, the Chief has been portrayed by Daniel Cudmore in Halo 4: Forward Unto Dawn and Pablo Schreiber in the Paramount+ series.

Cortana, voiced in the games by Jen Taylor, is the artificial intelligence (AI) who assists the Master Chief in the video games. She is one of many "smart" AIs, and is based on the brain of Dr. Catherine Halsey; the nature of her construction means she is subject to a finite lifespan. In Halo 4, Cortana begins to succumb to her age, and sacrifices herself to save Chief and Earth from the Forerunner Didact, but Halo 5: Guardians reveals that she had survived the ordeal. Having found access to the Domain, a Forerunner repository of knowledge, Cortana believes that AIs should serve as the galaxy's caretakers, putting her in conflict with her creators. In Halo Infinite, however, after Atriox seemingly defeats Chief which devastates her, Cortana finally destroys herself. Cortana has been called one of gaming's greatest characters, and one of the "50 Greatest Female Characters" and the heart of the franchise. The character's sex appeal has also been a focus on commentary.