I've never had any real friends. (...) Except you, Rajah.
Rajah is Jasmine's loyal and faithful pet tiger from the Aladdin franchise. His vocal effects are provided by Frank Welker (who also voices Abu).
He clearly loves Jasmine very much and is very protective of her. When the snooty Prince Achmed introduced himself to Jasmine, Rajah attacked him and tore a hole in his pants, although Jasmine implied that Rajah was trying to "play" with Achmed. He is later seen chewing on a piece of Achmed's underwear. 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. Nonetheless, he still sometimes growls at Aladdin as his way of saying hello, which initially concerned Aladdin after the latter returned from busting a band of thieves and retrieving their stolen treasure. During the events of the movie, he gets turned back into a cub by Jafar when he tried to help, although he later gets restored when Jafar is defeated. As such, until Jasmine met Aladdin, he was the only friend Jasmine had.'
Rajah had an even harder time getting comfortable around Iago, ex-bird of Jafar. When he regonzed 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 heroes' 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.
The Return of Jafar
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. When Abu saw Rajah nearby, he opened the cage, and Rajah recognized the parrot and snarled at him. Iago, terrified, begged Abu to close the cage again. But Rajah pounces on the cage, destroying it, and chases Iago into the palace, accidentally 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).
Aladdin: the Series
Although primarily a mere minor character in the TV series, Rajah played a some major roles in a few episodes.
For example, "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.
Aladdin and the King of Thieves
Rajah plays an extremely minor role in the third film of the franchise. At the end, when Jasmine and Aladdin are finally married, Rajah serves as Jasmine's usher.
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.
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 Sultan.