Cassian Jeron Andor is a fictional character in the Star Wars franchise, primarily portrayed by actor Diego Luna. Introduced in the feature film Rogue One (2016) as a co-lead, he is the titular protagonist of the prequel television series Andor (2022–2025).

He begins his life as an orphan on the abandoned mining planet Kenari. After being adopted and taken from his home by scavengers, he grows up on the industrial planet Ferrix. As a young man, he smuggles stolen Imperial ship components before joining the Rebel Alliance. Rogue One depicts Andor as a pilot and intelligence officer for the Rebel Alliance who leads a rebel unit called Rogue One in stealing plans for the Death Star, setting the events of the original Star Wars film in motion.

The character has received a mixed response from critics, with praise for Luna's performance but some criticism for the quality of the narrative guiding the character. As the first Mexican lead actor and one of the first Latino leads in a Star Wars film, his introduction in Rogue One was considered to be a milestone for Latino representation.

Though not initially named Cassian Andor, a "Cassian Andor–type character" appeared in the original treatment of Rogue One written by John Knoll, chief creative officer at Industrial Light & Magic and in the first draft of the script written by Gary Whitta. The character was created as a member of Rogue One, then commanded by a Rebel Alliance sergeant version of Jyn Erso. The original intention was to kill all members of the Rogue One team, including Cassian. However, fearing that Disney would not allow the ending, Knoll and Whitta wrote that Cassian escapes Scarif with the Death Star plans alongside Jyn Erso and, though their ship is destroyed by Darth Vader after they transfer the plans to Princess Leia, they narrowly survive in an escape pod. Whitta stated that having to "jump through so many hoops" to ensure survival indicated that Cassian and Jyn should die on Scarif. Producer Kathleen Kennedy and Disney ultimately approved the ending in which the entire crew dies. The main purpose of this action was believed to be for the characters to be ultimately replaced after the film by the crew of the original trilogy.

Tony Gilroy stated that the inspiration for Cassian's role in funding the rebellion comes from the book Young Stalin by Simon Sebag Mantefiore.

In May 2015, it was announced that Diego Luna had been cast in a lead role in Rogue One. Director Gareth Edwards wanted Cassian to be warm and likeable rather than the typical stoic, brooding action hero, leading to Edwards' decision to cast Luna early on. He was impressed by Luna's background in small, character-driven productions, especially as he wanted the film to tell a more personal story than previous Star Wars installments. Luna felt that his casting—and the casting of other actors who may be non-white and/or whose mother tongue is a language other than English—in the films' leading roles reflected a "modern approach" and a world in which "racial and cultural diversity is in fact making us richer and more interesting."

In his portrayal of the character, Luna speaks with his own, natural Mexican accent—a rarity for a franchise which has mostly featured actors with American or British accents. Luna stated that his accent was not an issue with the film's producers, who were happy with it. Luna also dubbed Andor's dialogue for the Spanish-language version of the film; the dub was recorded in Mexico City months before the film's theatrical release.

While filming Rogue One, Luna developed a personal backstory for Cassian to help him get into character. In an interview with Entertainment Weekly, he stated that he incorporated Mexican cultural influences into the character's backstory. He imagined the character to come from a "marginalized" background as a way to explain his unique accent in the Star Wars universe. He stated this backstory resonated with Andor showrunner Tony Gilroy, who also wanted to explain the character's distinctive accent.