Rajah was originally a circus tiger as a cub, who found his way into the Sultan's palace after escaping the touring circus group during a visit to Agrabah. He was discovered by a, then, young Princess Jasmine, who assumed the cub was a gift from her deceased mother. As a child, Jasmine's mother told the princess stories of a star named "Rajah", prompting Jasmine to name her new cub in honor of those stories. Once the Sultan discovers Rajah, he expresses the need to have the latter return to the circus, though his mind is eventually changed and he manages to purchase Rajah from his original owner.
Rajah is Jasmine's best friend and fierce protector. As such, he cares deeply for the princess, and repeatedly supports her throughout the course of the franchise, not once showing a hint of disloyalty or true aggression towards her (though he showed offense when Jasmine mentioned a lack of friends; absentmindedly forgetting Rajah for a brief moment). He is mostly known for being rather aggressive and intolerable, as he takes a disliking to anyone who annoys Jasmine, even slightly—including narcissistic suitors, "Prince Ali", and even the Sultan. However, when with Jasmine, Rajah is docile and gentle. He appears to represent Jasmine's overall character in this sense as she, too, can be either fierce or loving, depending on whom she is interacting with.
At first, Rajah wasn't too fond of Aladdin, and often growled at him, but by the end of the movie, he has grown more comfortable around him. He had an even harder time getting comfortable around Iago, ex-bird of Jafar. When he recognized the parrot, he tried to attack him before Aladdin stopped him. Even after the fully redeemed Iago kicked Jafar's lamp into the lava, destroying him forever, Rajah, though warmed up to the parrot, still has somewhat of a strained relationship with Iago; as he threatens to eat the cowardly parrot if he doesn't cooperate in doing our hero's requests.
Rajah is introduced with Princess Jasmine. He attacked one of Jasmine's snobby suitors and successfully got him to leave Agrabah. Later on, Jasmine decided to run away to escape the palace life, with Rajah assisting her in her escape, causing him to feel incredibly depressed afterwards. Later, Jasmine returned, and Rajah comforts her as she cries at the supposed loss of the boy she met at the Marketplace, unknown to her to be Aladdin. The next day, Prince Ali (Aladdin in disguise through the magic of his genie) visits Agrabah as a suitor for Jasmine. Jasmine and Rajah take immediate disliking to the prince because of his flashy appearance and nature. Aladdin then tries Genie's advice to be himself, eventually winning the heart of Jasmine in the process. At the battle with the evil royal vizier Jafar, Rajah is magically turned into a tiger cub and placed in a bird cage. After Jafar's defeat, Rajah is returned back to normal, celebrates the heroism of Aladdin and bids farewell to the now-freed Genie.
Rajah is a supporting character in the sequel. He is first seen snarling and seemingly ready to attack Aladdin as he arrived on Jasmine's balcony, but the tiger immediately pounces on the boy and gives him a welcoming lick. He also stops Abu when the latter attempted to steal the jeweled flower that Aladdin gave Jasmine earlier.
Later on, Iago, the sidekick of Jafar, unintentionally saved Aladdin's life. As a reward, Aladdin allowed him to stay at the palace. Iago in a birdcage, begs Abu to open it to let him out. When Abu saw Rajah nearby, he opened Iago's cage, and Rajah recognized the parrot and snarled at the him. Iago, terrified, begged Abu to close the cage again. But Rajah pounces on the cage, destroying it and chases Iago into the palace, unintentionally ruining the palace dinner and blowing Iago's cover to the whole palace. Rajah is then seen at the finale where he and the others welcome Iago into the palace after he saved Agrabah from a vengeful Jafar, although he did swipe his paw on Iago and place him underneath it in an attempt to shut him up when the latter protested Aladdin's decision to not be Grand Vizier (having planned to become Grand Vizier to Aladdin in the event that he became the Sultan).
Although primarily a mere minor character in the TV series (mostly due to difficulties with animating him), Rajah played a major role in some episodes.
For example, in "SandSwitch", when he, Abu and Iago were the only three unaffected by Sadira's use of an unspecified magical sand that somehow altered history so that Sadira was the princess and Jasmine the street rat; since the three animals were the only ones who knew that history wasn't the way it should be, the three escape the palace to find Jasmine and restore the world to normal.
A small running gag in the TV series is whenever Iago refuses our hero's requests (i.e watching out for Abu, stating he can't change the alternated time line), Rajah threatens to eat the parrot, and Iago relents.
Rajah plays an extremely minor role in the third film of the franchise. He appears during Jasmine and Aladdin's wedding at the film's epilogue — in during which, Rajah watches with Abu jumping on him in excitement and serves as Jasmine's usher.
Rajah plays a supporting role in Jasmine's segment of the film. He is first seen delivering Jasmine's list of royal errands for the day. Later on, when Jasmine becomes a substitute teacher for the Royal Academy, the students prove to be rather rambunctious and disruptive. In an attempt to solve the problem, Jasmine uses Rajah to scare the kids in check. Though it appears to be a successful plan at first, the children instead get excited at the sight of a "kitty", forcing both Rajah and Jasmine to escape by climbing up a tree.
In House of Mouse, Rajah makes a cameo appearance with some of his co-stars in the episode "Pete's House of Villains". Here, Jafar bans all the rest of the Aladdin cast from entering the newly-established House of Villains—including Rajah, but excluding Jasmine.
An emoji version of Rajah appeared in the Aladdin entry of the As Told by Emoji short series.
"Rajah" means "Indian prince" in Hindi and Arabic.
A slight goof happens when Rajah transforms into a cub. He meows like a house cat, and because of that, some stories say that Rajah is turned into a kitten instead of a cub. But in actuality, tiger cub cries sound nothing like house cat calls. However, this may have been an intended comedic moment.
Although tigers are traditionally found in South Asia and not the Middle East, it is not unreasonable to assume that because of the Sultan's wealth, he was perfectly capable of having one imported as a gift for Jasmine at some point. One subspecies of tiger, the Caspian tiger, did live in the Middle East, but it is now extinct.
The book "A Pet for a Princess" actually confirmed this, where it was revealed that Rajah was actually said to have been born at a traveling circus, and was bought by the Sultan.
Another book about the origins of Rajah, "Monkey Business", contradicts this by revealing that Abu set a tiger cub, later known as Rajah, free from a traveling circus cage.
At the end of the original film, when everything begins to return to normal, Rajah's face turns into that of Mickey Mouse for a split second.