Char Aznable (Japanese: シャア・アズナブル, Hepburn: Shā Azunaburu), born Casval Rem Deikun (Japanese: キャスバル・レム・ダイクン, Hepburn: Kyasubaru Remu Daikun) and also known as Édouard Mass (エドワウ・マス, Edowau Masu), is a fictional character from the Gundam franchise. He is originally one of the main antagonists in Mobile Suit Gundam working for the Principality of Zeon, named after his late father Zeon Zum Deikun, with the honorary title of "The Red Comet" (赤い彗星, Akai Suisei) during Gundam's One Year War. Despite having opposed Earth Federation soldier Amuro Ray several times, in the sequel Mobile Suit Zeta Gundam he becomes Quattro Bajeena (クワトロ・バジーナ, Kuwatoro Bajīna), an Anti-Earth Union Group (AEUG) pilot fighting alongside the series' main characters against the elitist Titans. In his final appearance in the Prime-UC in Char's Counterattack, he assumes leadership of the Neo Zeon movement, and becomes the titular antagonist of the film. An alternate Char debuts in Mobile Suit Gundam GQuuuuuuX, which sets in an alternate-UC branching timeline, he steals the Gundam and becomes its pilot instead of Amuro, setting the series' alternate events culminating in Zeon's victory of the One Year War, though Char would mysteriously disappear in the final battle.

Char became one of Gundam's most iconic characters, often overshadowing Amuro's popularity. He also appeared as the most popular male anime character in Animage's Anime Grand Prix poll as well as in several other polls highlighting his popularity in the Gundam franchise. His role in the original has often been praised alongside his rivalry with Amuro.

Char Aznable was based on historic fighter-pilot Manfred von Richthofen who shared a similar nickname, "Red Baron". As a result, many of Char's actions were similar to Richtofen's during World War I since Tomino wanted to illustrate the chaos produced by wars in Gundam. Amuro was introduced as an ordinary man in contrast to his rival the "Red Comet". This made Amuro hard to write as he was meant to oppose Char whom Tomino found more interesting. Tōru Furuya, who voiced Amuro, had fun in his work as during recordings of the series he befriended Char's voice Actor Shuichi Ikeda. However, he was not close to Tomino. Originally, Tomino did not want to include Amuro in Zeta Gundam and when trying to kill him, he failed to do it. As a result, he decided to put Amuro on a friendly relationship with Char. Furuya said that while Amuro also had popularity, he could not surpass his rival, Char, a common trait he sometimes find common in anime where there are rivalries. The name Char Aznable was inspired by Armenian-French singer and songwriter Charles Aznavour (シャルル・アズナヴール, Sharuru Azunavūru) and a character named Charkin in an earlier robot anime Reideen (ライディーン).

Born Casval Rem Deikun, he is the elder brother of Artesia Som Deikun and son of Zeon Zum Deikun, a dignitary who spoke out for peace between spacenoids and earthlings and founded the Zeon Republic. Following their father's supposed heart attack, which was suspected to be an assassination orchestrated by Deikun's deputy Degwin Sodo Zabi, young Casval and his sister Artesia escape to Earth with the help of family friend Jimba Ral (father of Ramba Ral). While the Zabi family rises to power, the two Deikun children spend several years living a luxurious life under the guardianship of the aristocratic Don Teabolo Mass, who names them Edward and Sayla, and treats them like his own children. During this time, Jimba Ral constantly reminds Casval of the Zabi Family's betrayal of his father. After narrowly escaping another attempt on their lives (in which Jimba Ral dies), they flee to the Texas Colony.

They live for a time in a house set up by Texas Colony's chief manager Roger Aznable, still under Teabolo Mass's care. They meet Roger's son Char Aznable, and discover that he and Casval are nearly identical, except Casval's eyes are blue while Char's are brown. Eventually Char is taken in by Gihren Zabi's propaganda, and against his father's wishes sets off for officer training school. Casval decides to accompany him under the guise of looking out for his friend. Kycilia Zabi finds out that Casval is headed back to Side 3, and without consulting Gihren, orders Casval's death. Both near-identical boys are booked to leave on the same flight, but an antique pistol and fake explosives are found in Char's bag. Not wanting to miss the entrance exam, Char accepts Casval's suggestion to swap clothes in the restroom. Char boards the ship under the name Edward Mass, while Casval, under the name Char Aznable is detained overnight. Shortly after departure, the ship explodes and kills everyone aboard, likely due to the work of Kycilia's henchmen. "Edward Mass" is listed among the dead and Casval takes on the name Char, enters the Zeon Military Academy and begins wearing sunglasses to hide his eye color (as it wouldn't match any of the real Char's IDs).

After entering the academy, Char excels in his training and befriends Garma Zabi. As relations between the Zeon Republic (which has been renamed the Principality of Zeon) and the Federation deteriorate, the Federation increases their troop strength in Side 3. There is widespread fear that this troop increase is in fact an invasion and occupation force. On the eve of troop increase, Casval incites Garma to lead other students in the academy to storm the Federation base and subdue the stationed troops. For this action Casval is stripped of his rank and expelled from the academy. He travels to Earth and works at the construction site of Federation headquarters in Jaburo. After hostility breaks out between Zeon and the Federation, he returns to Side 3 and joins the Zeon mobile suit assault forces under the command of Admiral Dozle Zabi. He displays superior fighting abilities during the Battle of Loum, single-handedly destroying five Federation Magellan-class battleships by pushing his red-painted Zaku to fly at a breakneck speed, which earned him the nickname "Red Comet". He was promoted an exceptional two ranks to Lieutenant Commander.

On his way back from a mission to clear out guerrilla forces of the Federation Forces, he discovers a new type of ship (the White Base). By tracking it, he obtains information that the Federation Forces are secretly developing mobile suits in Side 7. When his subordinates sent out on a reconnaissance mission are destroyed by the RX-78-2 Gundam, including their Zaku, he sneaks into the colony himself and is reunited with his sister, Artesia (Sayla), who had evacuated to the White Base to serve in the army, and then has his first confrontation with his eventual rival, Amuro Ray. Although Char overwhelms Amuro, who is unfamiliar with combat, from start to finish, he is unable to overcome the Gundam's strong armor that can bounce back his attack and its powerful beam rifle.

Later, he is ordered to capture or destroy the White Base and the Gundam, and pursues the White Base as it escapes from Side 7. He launches numerous attacks, including infiltrating the Federation Forces' space fortress Luna II, where the White Base has escaped, and sabotaging it, but he fails. He loses many of his men and Zaku units. However, during a surprise attack aimed at the White Base's entry into the atmosphere, despite the numerous casualty of his squad, he succeeds in bringing it down under Zeon controlled territory, which is under the leadership of Garma.